Document System.IO.StreamReader (#3530)

* Document System.IO.StreamReader

* Apply suggestions from code review

Co-Authored-By: Maira Wenzel <[email protected]>

* Update xml/System.IO/StreamReader.xml

Author: carlossanlop

xml/System.IO/StreamReader.xml

@@ -1513,10 +1513,13 @@ Following a call to <xref:System.IO.StreamReader.Close%2A>, any operations on th
         <Parameter Name="buffer" Type="System.Span&lt;System.Char&gt;" Index="0" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="buffer">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="buffer">When this method returns, contains the specified span of characters replaced by the characters read from the current source.</param>
+        <summary>Reads the characters from the current stream into a span.</summary>
+        <returns>The number of characters that have been read, or 0 if at the end of the stream and no data was read. The number will be less than or equal to the <paramref name="buffer" /> length, depending on whether the data is available within the stream.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.IO.IOException">The number of characters read from the stream is larger than the <paramref name="buffer" /> length.</exception>
+        <exception cref="T:System.ArgumentNullException">
+          <paramref name="buffer" /> is <see langword="null" />.</exception>
       </Docs>
     </Member>
     <Member MemberName="Read">
@@ -1634,10 +1637,10 @@ Following a call to <xref:System.IO.StreamReader.Close%2A>, any operations on th
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="1" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="buffer">To be added.</param>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="buffer">When this method returns, contains the specified memory block of characters replaced by the characters read from the current source.</param>
+        <param name="cancellationToken">The token to monitor for cancellation requests. The default value is <see cref="P:System.Threading.CancellationToken.None" />.</param>
+        <summary>Asynchronously reads the characters from the current stream into a memory block.</summary>
+        <returns>A value task that represents the asynchronous read operation. The value of the type parameter of the value task contains the number of characters that have been read, or 0 if at the end of the stream and no data was read. The number will be less than or equal to the <paramref name="buffer" /> length, depending on whether the data is available within the stream.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>
@@ -1743,10 +1746,14 @@ Following a call to <xref:System.IO.StreamReader.Close%2A>, any operations on th
         <Parameter Name="buffer" Type="System.Span&lt;System.Char&gt;" Index="0" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="buffer">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="buffer">When this method returns, contains the specified span of characters replaced by the characters read from the current source.</param>
+        <summary>Reads the characters from the current stream and writes the data to a buffer.</summary>
+        <returns>The number of characters that have been read. The number will be less than or equal to the <paramref name="buffer" /> length, depending on whether all input characters have been read.</returns>
         <remarks>To be added.</remarks>
+        <exception cref="T:System.ArgumentNullException">
+          <paramref name="buffer" /> is <see langword="null" />.</exception>
+        <exception cref="T:System.ObjectDisposedException">The <see cref="T:System.IO.StreamReader" /> is closed.</exception>
+        <exception cref="T:System.IO.IOException">An I/O error occurred.</exception>
       </Docs>
     </Member>
     <Member MemberName="ReadBlock">
@@ -1840,10 +1847,10 @@ Following a call to <xref:System.IO.StreamReader.Close%2A>, any operations on th
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="1" FrameworkAlternate="netcore-2.1;netcore-2.2;netcore-3.0;netstandard-2.1" />
       </Parameters>
       <Docs>
-        <param name="buffer">To be added.</param>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="buffer">When this method returns, contains the specified memory block of characters replaced by the characters read from the current source.</param>
+        <param name="cancellationToken">The token to monitor for cancellation requests. The default value is <see cref="P:System.Threading.CancellationToken.None" />.</param>
+        <summary>Asynchronously reads the characters from the current stream and writes the data to a buffer.</summary>
+        <returns>A value task that represents the asynchronous read operation. The value of the type parameter of the value task contains the total number of characters read into the buffer. The result value can be less than the number of characters requested if the number of characters currently available is less than the requested number, or it can be 0 (zero) if the end of the stream has been reached.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>