Clean up doc comments for PushStreamContent (#311)

Fixes https://github.com/aspnet/AspNetWebStack/issues/310

src/System.Net.Http.Formatting/PushStreamContent.cs

@@ -25,7 +25,7 @@ namespace System.Net.Http
         /// Initializes a new instance of the <see cref="PushStreamContent"/> class. The
         /// <paramref name="onStreamAvailable"/> action is called when an output stream
         /// has become available allowing the action to write to it directly. When the
-        /// stream is closed, it will signal to the content that is has completed and the 
+        /// stream is closed, it will signal to the content that it has completed and the
         /// HTTP request or response will be completed.
         /// </summary>
         /// <param name="onStreamAvailable">The action to call when an output stream is available.</param>
@@ -37,8 +37,9 @@ namespace System.Net.Http
         /// <summary>
         /// Initializes a new instance of the <see cref="PushStreamContent"/> class.
         /// </summary>
-        /// <param name="onStreamAvailable">The action to call when an output stream is available. The stream is automatically
+        /// <param name="onStreamAvailable">The action to call when an output stream is available. When the
-        /// closed when the return task is completed.</param>
+        /// output stream is closed or disposed, it will signal to the content that it has completed and the
+        /// HTTP request or response will be completed.</param>
         public PushStreamContent(Func<Stream, HttpContent, TransportContext, Task> onStreamAvailable)
             : this(onStreamAvailable, (MediaTypeHeaderValue)null)
         {
@@ -47,6 +48,8 @@ namespace System.Net.Http
         /// <summary>
         /// Initializes a new instance of the <see cref="PushStreamContent"/> class with the given media type.
         /// </summary>
+        /// <param name="onStreamAvailable">The action to call when an output stream is available.</param>
+        /// <param name="mediaType">The value of the Content-Type content header on an HTTP response.</param>
         public PushStreamContent(Action<Stream, HttpContent, TransportContext> onStreamAvailable, string mediaType)
             : this(Taskify(onStreamAvailable), new MediaTypeHeaderValue(mediaType))
         {
@@ -55,6 +58,10 @@ namespace System.Net.Http
         /// <summary>
         /// Initializes a new instance of the <see cref="PushStreamContent"/> class with the given media type.
         /// </summary>
+        /// <param name="onStreamAvailable">The action to call when an output stream is available. When the
+        /// output stream is closed or disposed, it will signal to the content that it has completed and the
+        /// HTTP request or response will be completed.</param>
+        /// <param name="mediaType">The value of the Content-Type content header on an HTTP response.</param>
         public PushStreamContent(Func<Stream, HttpContent, TransportContext, Task> onStreamAvailable, string mediaType)
             : this(onStreamAvailable, new MediaTypeHeaderValue(mediaType))
         {
@@ -63,6 +70,8 @@ namespace System.Net.Http
         /// <summary>
         /// Initializes a new instance of the <see cref="PushStreamContent"/> class with the given <see cref="MediaTypeHeaderValue"/>.
         /// </summary>
+        /// <param name="onStreamAvailable">The action to call when an output stream is available.</param>
+        /// <param name="mediaType">The value of the Content-Type content header on an HTTP response.</param>
         public PushStreamContent(Action<Stream, HttpContent, TransportContext> onStreamAvailable, MediaTypeHeaderValue mediaType)
             : this(Taskify(onStreamAvailable), mediaType)
         {
@@ -71,6 +80,10 @@ namespace System.Net.Http
         /// <summary>
         /// Initializes a new instance of the <see cref="PushStreamContent"/> class with the given <see cref="MediaTypeHeaderValue"/>.
         /// </summary>
+        /// <param name="onStreamAvailable">The action to call when an output stream is available. When the
+        /// output stream is closed or disposed, it will signal to the content that it has completed and the
+        /// HTTP request or response will be completed.</param>
+        /// <param name="mediaType">The value of the Content-Type content header on an HTTP response.</param>
         public PushStreamContent(Func<Stream, HttpContent, TransportContext, Task> onStreamAvailable, MediaTypeHeaderValue mediaType)
         {
             if (onStreamAvailable == null)