Update SslClientAuthenticationOptions.TargetHost (#9583)

Author: rzikm

xml/System.Net.Security/SslClientAuthenticationOptions.xml

@@ -473,9 +473,9 @@
         <ReturnType>System.String</ReturnType>
       </ReturnValue>
       <Docs>
-        <summary>Gets or sets the name of the server the client is trying to connect to. That name is used for server certificate validation. It can be a DNS name or an IP address.</summary>
-        <value>To be added.</value>
-        <remarks>To be added.</remarks>
+        <summary>Gets or sets the name of the server the client is trying to connect to. The name is used for server certificate validation and can be a DNS name or an IP address.</summary>
+        <value>The name of the server the client is trying to connect to. If set to <see langword="null" /> (.NET 7 and later versions only) or an empty string, the client doesn't send the host name in the Server Name Indication extension.</value>
+        <remarks>If the value is <see langword="null" /> or an empty string, you should also provide a <see cref="T:System.Net.Security.RemoteCertificateValidationCallback" /> and validate the subject of the server's certificate.</remarks>
       </Docs>
     </Member>
   </Members>