Add missing DateTime/DateTimeOffset/TimeSpan docs (#3500)

* Add missing DateTime/DateTimeOffset/TimeSpan docs

* Update xml/System/DateTime.xml

Co-Authored-By: Carlos Sanchez Lopez <[email protected]>

* Update xml/System/DateTimeOffset.xml

Co-Authored-By: Carlos Sanchez Lopez <[email protected]>

* fix build

* string representation -> char span

Author: krwq

xml/System/DateTime.xml

@@ -8102,7 +8102,7 @@ The value of the current <xref:System.DateTime> object is formatted using the pa
       <Docs>
         <param name="s">A string containing a date and time to convert.</param>
         <param name="result">When this method returns, contains the <see cref="T:System.DateTime" /> value equivalent to the date and time contained in <paramref name="s" />, if the conversion succeeded, or <see cref="F:System.DateTime.MinValue" /> if the conversion failed. The conversion fails if the <paramref name="s" /> parameter is <see langword="null" />, is an empty string (""), or does not contain a valid string representation of a date and time. This parameter is passed uninitialized.</param>
-        <summary>To be added.</summary>
+        <summary>Converts the specified char span of a date and time to its <see cref="T:System.DateTime" /> equivalent and returns a value that indicates whether the conversion succeeded.</summary>
         <returns><see langword="true" /> if the <paramref name="s" /> parameter was converted successfully; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
@@ -8446,13 +8446,13 @@ The value of the current <xref:System.DateTime> object is formatted using the pa
         <Parameter Name="result" Type="System.DateTime" RefType="out" Index="4" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="s">To be added.</param>
-        <param name="formats">To be added.</param>
-        <param name="provider">To be added.</param>
-        <param name="style">To be added.</param>
-        <param name="result">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="s">The span containing the string to parse.</param>
+        <param name="formats">An array of allowable formats of <paramref name="s" />.</param>
+        <param name="provider">An object that supplies culture-specific formatting information about <paramref name="s" />.</param>
+        <param name="style">A bitwise combination of enumeration values that defines how to interpret the parsed date in relation to the current time zone or the current date. A typical value to specify is <see cref="F:System.Globalization.DateTimeStyles.None" />.</param>
+        <param name="result">When this method returns, contains the <see cref="T:System.DateTime" /> value equivalent to the date and time contained in <paramref name="s" />, if the conversion succeeded, or <see cref="F:System.DateTime.MinValue" /> if the conversion failed. The conversion fails if the <paramref name="s" /> parameter is <see langword="null" />, is <see cref="F:System.String.Empty" />, or does not contain a valid string representation of a date and time. This parameter is passed uninitialized.</param>
+        <summary>Converts the specified char span of a date and time to its <see cref="T:System.DateTime" /> equivalent and returns a value that indicates whether the conversion succeeded.</summary>
+        <returns><see langword="true" /> if the <paramref name="s" /> parameter was converted successfully; otherwise, <see langword="false" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -8706,7 +8706,7 @@ The value of the current <xref:System.DateTime> object is formatted using the pa
         <ReturnType>System.DateTime</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>The value of this constant is equivalent to 00:00:00.0000000 UTC, January 1, 1970, in the Gregorian calendar. <see cref="F:System.DateTime.UnixEpoch" /> defines the point in time when Unix time is equal to 0.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System/DateTimeOffset.xml

@@ -6064,7 +6064,7 @@ Strings that do not specify a UTC offset are assumed to have the offset of the l
         <ReturnType>System.DateTimeOffset</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>To be added.</summary>
+        <summary>The value of this constant is equivalent to 00:00:00.0000000 UTC, January 1, 1970, in the Gregorian calendar. <see cref="F:System.DateTimeOffset.UnixEpoch" /> defines the point in time when Unix time is equal to 0.</summary>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System/TimeSpan.xml

@@ -818,9 +818,9 @@
         <Parameter Name="divisor" Type="System.Double" Index="0" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="divisor">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="divisor">The value to be divided by.</param>
+        <summary>Returns a new <see cref="T:System.TimeSpan" /> object which value is the result of division of this instance and the specified <paramref name="divisor" />.</summary>
+        <returns>A new object that represents the value of this instance divided by the value of <paramref name="divisor" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -851,9 +851,9 @@
         <Parameter Name="ts" Type="System.TimeSpan" Index="0" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="ts">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="ts">The value to be divided by.</param>
+        <summary>Returns a new <see cref="T:System.Double" /> value which is the result of division of this instance and the specified <paramref name="ts" />.</summary>
+        <returns>A new value that represents result of division of this instance by the value of the <paramref name="ts" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1943,9 +1943,9 @@
         <Parameter Name="factor" Type="System.Double" Index="0" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="factor">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="factor">The value to be multiplied by.</param>
+        <summary>Returns a new <see cref="T:System.TimeSpan" /> object which value is the result of multiplication of this instance and the specified <paramref name="factor" />.</summary>
+        <returns>A new object that represents the value of this instance multiplied by the value of <paramref name="factor" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -2085,10 +2085,10 @@
         <Parameter Name="divisor" Type="System.Double" Index="1" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="timeSpan">To be added.</param>
-        <param name="divisor">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="timeSpan">Dividend or the value to be divided.</param>
+        <param name="divisor">The value to be divided by.</param>
+        <summary>Returns a new <see cref="T:System.TimeSpan" /> object which value is the result of division of <paramref name="timeSpan" /> instance and the specified <paramref name="divisor" />.</summary>
+        <returns>A new object that represents the value of <paramref name="timeSpan" /> instance divided by the value of <paramref name="divisor" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -2120,10 +2120,10 @@
         <Parameter Name="t2" Type="System.TimeSpan" Index="1" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="t1">To be added.</param>
-        <param name="t2">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="t1">Divident or the value to be divided.</param>
+        <param name="t2">The value to be divided by.</param>
+        <summary>Returns a new <see cref="T:System.Double" /> value which is the result of division of <paramref name="t1" /> instance and the specified <paramref name="t2" />.</summary>
+        <returns>A new value that represents result of division of <paramref name="t1" /> instance by the value of the <paramref name="t2" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -2533,10 +2533,10 @@
         <Parameter Name="timeSpan" Type="System.TimeSpan" Index="1" FrameworkAlternate="netcore-2.0;netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="factor">To be added.</param>
-        <param name="timeSpan">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="factor">The value to be multiplied by.</param>
+        <param name="timeSpan">The value to be multiplied.</param>
+        <summary>Returns a new <see cref="T:System.TimeSpan" /> object which value is the result of multiplication of <paramref name="timeSpan" /> instance and the specified <paramref name="factor" />.</summary>
+        <returns>A new object that represents the value of <paramref name="timeSpan" /> instance multiplied by the value of <paramref name="factor" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -3205,12 +3205,12 @@ When a time interval component in the string to be parsed contains more than sev
         <Parameter Name="styles" Type="System.Globalization.TimeSpanStyles" Index="3" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="input">To be added.</param>
-        <param name="format">To be added.</param>
-        <param name="formatProvider">To be added.</param>
-        <param name="styles">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="input">A span that specifies the time interval to convert.</param>
+        <param name="format">A standard or custom format string that defines the required format of <paramref name="input" />.</param>
+        <param name="formatProvider">An object that provides culture-specific formatting information.</param>
+        <param name="styles">A bitwise combination of enumeration values that defines the style elements that may be present in <paramref name="input" />.</param>
+        <summary>Converts the char span of a time interval to its <see cref="T:System.TimeSpan" /> equivalent by using the specified format and culture-specific format information. The format of the string representation must match the specified format exactly.</summary>
+        <returns>A time interval that corresponds to <paramref name="input" />, as specified by <paramref name="format" /> and <paramref name="formatProvider" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -3242,12 +3242,12 @@ When a time interval component in the string to be parsed contains more than sev
         <Parameter Name="styles" Type="System.Globalization.TimeSpanStyles" Index="3" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="input">To be added.</param>
-        <param name="formats">To be added.</param>
-        <param name="formatProvider">To be added.</param>
-        <param name="styles">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="input">A span that specifies the time interval to convert.</param>
+        <param name="formats">An array of standard or custom format strings that define the required format of <paramref name="input" />.</param>
+        <param name="formatProvider">An object that provides culture-specific formatting information.</param>
+        <param name="styles">A bitwise combination of enumeration values that defines the style elements that may be present in input.</param>
+        <summary>Converts the string representation of a time interval to its <see cref="T:System.TimeSpan" /> equivalent by using the specified formats, culture-specific format information, and styles. The format of the string representation must match one of the specified formats exactly.</summary>
+        <returns>A time interval that corresponds to <paramref name="input" />, as specified by <paramref name="formats" />, <paramref name="formatProvider" />, and <paramref name="styles" />.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>