Automatic port of System.IO.Pipelines PipeReader/PipeWriter CompleteAsync (dotnet#3007)

* Document System.IO.Pipelines PipeReader/PipeWriter CompleteAsync

* that's -> that is

* Minor updates.

* Minor changes.

* Update PipeReader.xml

Author: carlossanlop

xml/System.IO.Pipelines/PipeReader.xml

@@ -1,4 +1,4 @@
-<Type Name="PipeReader" FullName="System.IO.Pipelines.PipeReader">
+<Type Name="PipeReader" FullName="System.IO.Pipelines.PipeReader">
   <TypeSignature Language="C#" Value="public abstract class PipeReader" />
   <TypeSignature Language="ILAsm" Value=".class public auto ansi abstract beforefieldinit PipeReader extends System.Object" />
   <TypeSignature Language="DocId" Value="T:System.IO.Pipelines.PipeReader" />
@@ -184,9 +184,9 @@
         <Parameter Name="exception" Type="System.Exception" Index="0" FrameworkAlternate="dotnet-plat-ext-3.0" />
       </Parameters>
       <Docs>
-        <param name="exception">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="exception">An optional exception that indicates the failure that caused the reader to complete.</param>
+        <summary>Marks the current pipe reader instance as being complete, meaning no more data will be read from it.</summary>
+        <returns>A value task that represents the asynchronous complete operation.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>

xml/System.IO.Pipelines/PipeWriter.xml

@@ -1,4 +1,4 @@
-<Type Name="PipeWriter" FullName="System.IO.Pipelines.PipeWriter">
+<Type Name="PipeWriter" FullName="System.IO.Pipelines.PipeWriter">
   <TypeSignature Language="C#" Value="public abstract class PipeWriter : System.Buffers.IBufferWriter&lt;byte&gt;" />
   <TypeSignature Language="ILAsm" Value=".class public auto ansi abstract beforefieldinit PipeWriter extends System.Object implements class System.Buffers.IBufferWriter`1&lt;unsigned int8&gt;" />
   <TypeSignature Language="DocId" Value="T:System.IO.Pipelines.PipeWriter" />
@@ -161,9 +161,9 @@
         <Parameter Name="exception" Type="System.Exception" Index="0" FrameworkAlternate="dotnet-plat-ext-3.0" />
       </Parameters>
       <Docs>
-        <param name="exception">To be added.</param>
-        <summary>To be added.</summary>
-        <returns>To be added.</returns>
+        <param name="exception">An optional exception that indicates the failure that caused the pipeline to complete.</param>
+        <summary>Marks the current pipe writer instance as being complete, meaning no more data will be written to it.</summary>
+        <returns>A value task that represents the asynchronous complete operation.</returns>
         <remarks>To be added.</remarks>
       </Docs>
     </Member>