Add HttpContent missing API (#4748)

Co-authored-by: Jan Jahoda <[email protected]>

Author: Jan Jahoda

xml/System.Net.Http/HttpContent.xml

@@ -226,11 +226,18 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="1" FrameworkAlternate="net-5.0" />
       </Parameters>
       <Docs>
-        <param name="stream">To be added.</param>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <param name="stream">The target stream.</param>
+        <param name="cancellationToken">The cancellation token to cancel the operation.</param>
+        <summary>Serialize the HTTP content into a stream of bytes and copies it to the stream object provided as the <paramref name="stream" /> parameter.</summary>
+        <returns>The task object representing the asynchronous operation.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[  
+  
+## Remarks  
+ This operation will not block. The returned <xref:System.Threading.Tasks.Task> object will complete after all of the content has been written to the stream object passed as the `stream` parameter.  
+  
+ ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="CopyToAsync">
@@ -257,12 +264,19 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="2" FrameworkAlternate="net-5.0" />
       </Parameters>
       <Docs>
-        <param name="stream">To be added.</param>
-        <param name="context">To be added.</param>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <param name="stream">The target stream.</param>
+        <param name="context">Information about the transport (channel binding token, for example). This parameter may be <see langword="null" />.</param>
+        <param name="cancellationToken">The cancellation token to cancel the operation.</param>
+        <summary>Serialize the HTTP content into a stream of bytes and copies it to the stream object provided as the <paramref name="stream" /> parameter.</summary>
+        <returns>The task object representing the asynchronous operation.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[  
+  
+## Remarks  
+ This operation will not block. The returned <xref:System.Threading.Tasks.Task> object will complete after all of the content has been written to the stream object passed as the `stream` parameter.  
+  
+ ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="CreateContentReadStream">
@@ -688,10 +702,19 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="0" FrameworkAlternate="net-5.0" />
       </Parameters>
       <Docs>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <param name="cancellationToken">The cancellation token to cancel the operation.</param>
+        <summary>Serialize the HTTP content to a byte array as an asynchronous operation.</summary>
+        <returns>The task object representing the asynchronous operation.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[  
+  
+## Remarks  
+ This operation will not block. The returned <xref:System.Threading.Tasks.Task%601> object will complete after all of the content has been written as a byte array.  
+  
+ Once the operation completes, the  <xref:System.Threading.Tasks.Task%601.Result%2A> property on the returned task object contains the byte array with the HTTP content.  
+  
+ ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ReadAsStream">
@@ -817,10 +840,19 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="0" FrameworkAlternate="net-5.0" />
       </Parameters>
       <Docs>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <param name="cancellationToken">The cancellation token to cancel the operation.</param>
+        <summary>Serialize the HTTP content and return a stream that represents the content as an asynchronous operation.</summary>
+        <returns>The task object representing the asynchronous operation.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[  
+  
+## Remarks  
+ This operation will not block. The returned <xref:System.Threading.Tasks.Task%601> object will complete after all of the stream that represents content has been read.  
+  
+ Once the operation completes, the  <xref:System.Threading.Tasks.Task%601.Result%2A> property on the returned task object contains the stream that represents the HTTP content. The returned stream can then be used to read the content using various stream APIs.  
+  
+ ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="ReadAsStringAsync">
@@ -893,10 +925,19 @@
         <Parameter Name="cancellationToken" Type="System.Threading.CancellationToken" Index="0" FrameworkAlternate="net-5.0" />
       </Parameters>
       <Docs>
-        <param name="cancellationToken">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
-        <remarks>To be added.</remarks>
+        <param name="cancellationToken">The cancellation token to cancel the operation.</param>
+        <summary>Serialize the HTTP content to a string as an asynchronous operation.</summary>
+        <returns>The task object representing the asynchronous operation.</returns>
+        <remarks>
+          <format type="text/markdown"><![CDATA[  
+  
+## Remarks  
+ This operation will not block. The returned <xref:System.Threading.Tasks.Task%601> object will complete after all of the content has been written as a string.  
+  
+ Once the operation completes, the  <xref:System.Threading.Tasks.Task%601.Result%2A> property on the returned task object contains the string with the HTTP content.  
+  
+ ]]></format>
+        </remarks>
       </Docs>
     </Member>
     <Member MemberName="SerializeToStream">