WinHttpHandler clean up and removal note (#4692)

* Contributes to dotnet/docs#19727

Author: gewarren

xml/System.Net.Http/WinHttpHandler.xml

@@ -23,19 +23,24 @@
   <Interfaces />
   <Docs>
     <summary>
-      <see cref="T:System.Net.Http.WinHttpHandler" /> is a specialty message handler based on the WinHTTP interface of Windows and is intended for use in server environments. This class is also available for use in Desktop apps by installing it as a NuGet package. For more information about installing this class for use in Desktop apps, see [System.Net.Http.WinHttpHandler](https://go.microsoft.com/fwlink/?LinkId=620067).</summary>
+      Handles messages based on the WinHTTP interface of Windows. This class is intended for use in server environments.</summary>
     <remarks>
       <format type="text/markdown"><![CDATA[  
   
-## Remarks  
+## Remarks
+
  <xref:System.Net.Http.WinHttpHandler> is similar to other existing classes such as <xref:System.Net.Http.HttpClientHandler>. <xref:System.Net.Http.WinHttpHandler> provides a handler underneath an <xref:System.Net.Http.HttpClient> instance and is used to send HTTP requests out to a server and receive server responses.  
   
- <xref:System.Net.Http.WinHttpHandler> is designed to be used primarily in server environments by ASP.NET Core and other .NET applications that communicate with HTTP servers. <xref:System.Net.Http.WinHttpHandler> also provides developers with more granular control over the application's HTTP communication than the <xref:System.Net.Http.HttpClientHandler> class. This allows developers to implement more advanced HTTP scenarios or modify system defaults (for example, proxy settings, timeouts and server SSL certificate validation).  
-  
- <xref:System.Net.Http.WinHttpHandler> is not intended to be a replacement for <xref:System.Net.Http.HttpClientHandler>, it is a more advanced version provided for scenarios where <xref:System.Net.Http.HttpClientHandler> is insufficient for developers. <xref:System.Net.Http.WinHttpHandler> is implemented as a thin wrapper on the WinHTTP interface of Windows and is only supported on Windows systems.  
+ <xref:System.Net.Http.WinHttpHandler> is designed to be used primarily in server environments by ASP.NET Core and other .NET applications that communicate with HTTP servers. <xref:System.Net.Http.WinHttpHandler> also provides developers with more granular control over the application's HTTP communication than the <xref:System.Net.Http.HttpClientHandler> class. This allows developers to implement more advanced HTTP scenarios or modify system defaults (for example, proxy settings, timeouts, and server SSL certificate validation).  
   
- When using a chain of multiple handlers, <xref:System.Net.Http.WinHttpHandler> should be at the bottom of the chain.  
+ <xref:System.Net.Http.WinHttpHandler> is not intended to be a replacement for <xref:System.Net.Http.HttpClientHandler>. Instead, it's a more advanced version that's provided for scenarios where <xref:System.Net.Http.HttpClientHandler> is insufficient. <xref:System.Net.Http.WinHttpHandler> is implemented as a thin wrapper on the WinHTTP interface of Windows and is only supported on Windows systems.  
   
+ When using a chain of multiple handlers, <xref:System.Net.Http.WinHttpHandler> should be at the bottom of the chain.
+
+This class is also available for use in Desktop apps by installing it as a NuGet package. For more information, see [System.Net.Http.WinHttpHandler NuGet package](https://www.nuget.org/packages/System.Net.Http.WinHttpHandler/).
+
+Starting in .NET 5.0, <xref:System.Net.Http.WinHttpHandler> is no longer included in the *System.Net.Http.dll* assembly as part of the .NET runtime. For more information, see [WinHttpHandler removed from .NET runtime](/dotnet/core/compatibility/3.1-5.0#winhttphandler-removed-from-net-runtime).
+
  ]]></format>
     </remarks>
   </Docs>
@@ -95,7 +100,7 @@
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- The default value for this property is GZip &#124; Deflate.  
+ The default value for this property is `GZip | Deflate`.
   
  ]]></format>
         </remarks>
@@ -126,12 +131,13 @@
       </ReturnValue>
       <Docs>
         <summary>Gets or sets a value that indicates whether the handler should follow HTTP redirection responses.</summary>
-        <value>To be added.</value>
+        <value><see langword="true" /> to follow HTTP redirection responses; otherwise, <see langword="false" />. The default is <see langword="true" />.</value>
         <remarks>
           <format type="text/markdown"><![CDATA[  
   
-## Remarks  
- The default value for this property is true. In this configuration, all HTTP redirect responses from the server will be followed automatically except if they are redirecting from an HTTPS endpoint to an HTTP endpoint.  
+## Remarks
+
+When this property is set to `true`, all HTTP redirect responses from the server will be followed automatically except if they are redirecting from an HTTPS endpoint to an HTTP endpoint.  
   
  ]]></format>
         </remarks>
@@ -162,15 +168,8 @@
       </ReturnValue>
       <Docs>
         <summary>Gets or sets a value that indicates whether to check the revocation list of certificates during SSL certificate validation.</summary>
-        <value>To be added.</value>
-        <remarks>
-          <format type="text/markdown"><![CDATA[  
-  
-## Remarks  
- The default value for this property is false.  
-  
- ]]></format>
-        </remarks>
+        <value><see langword="true" /> to check the revocation list of certificates during SSL certificate validation; otherwise, <see langword="false" />. The default is <see langword="false" />.</value>
+        <remarks>To be added.</remarks>
       </Docs>
     </Member>
     <Member MemberName="ClientCertificateOption">
@@ -234,7 +233,7 @@
         <ReturnType>System.Security.Cryptography.X509Certificates.X509Certificate2Collection</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>Gets or sets a collection of client authentication SSL certificates that are used for client authentication by the Handler if the <see cref="P:System.Net.Http.WinHttpHandler.ClientCertificateOption" /> property is set to Manual.</summary>
+        <summary>Gets a collection of client authentication SSL certificates that are used for client authentication by the handler if the <see cref="P:System.Net.Http.WinHttpHandler.ClientCertificateOption" /> property is set to <see langword="Manual" />.</summary>
         <value>To be added.</value>
         <remarks>
           <format type="text/markdown"><![CDATA[  
@@ -573,7 +572,7 @@
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- The default value for this property is false.  
+ The default value for this property is `false`.  
   
  ]]></format>
         </remarks>
@@ -639,7 +638,7 @@
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- The default value for this property is null.  
+ The default value for this property is `null`.  
   
  ]]></format>
         </remarks>
@@ -814,12 +813,12 @@
       </ReturnValue>
       <Docs>
         <summary>Gets or sets a callback method to validate the server certificate. This callback is part of the SSL handshake.</summary>
-        <value>The callback should return true if the server certificate is considered valid and the request should be sent. Otherwise, return false.</value>
+        <value>The callback should return <see langword="true" /> if the server certificate is considered valid and the request should be sent. Otherwise, return <see langword="false" />.</value>
         <remarks>
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- The default value is null. If this property is null, the server certificate will be validated using standard well-known certificate authorities.  
+ The default value is `null`. If this property is `null`, the server certificate is validated using standard well-known certificate authorities.  
   
  ]]></format>
         </remarks>
@@ -855,7 +854,7 @@
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- The default value for this property is null.  
+ The default value for this property is `null`.  
   
  ]]></format>
         </remarks>
@@ -891,7 +890,7 @@
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- The default value is SslProtocols.Tls &#124; SslProtocols.Tls11 &#124; SslProtocols.Tls12.  
+ The default value is `SslProtocols.Tls | SslProtocols.Tls11 | SslProtocols.Tls12`.
   
  ]]></format>
         </remarks>