Differentiate Extensions doc comments between client and server capabilities

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Protocol/ClientCapabilities.cs

@@ -105,8 +105,7 @@ public McpTasksCapability? Tasks
     /// </para>
     /// <para>
     /// Extensions provide a framework for extending the Model Context Protocol while maintaining
-    /// interoperability. Both clients and servers advertise extension support via this field during
-    /// the initialization handshake.
+    /// interoperability. Clients advertise extension support via this field during the initialization handshake.
     /// </para>
     /// </remarks>
     [Experimental(Experimentals.Extensions_DiagnosticId, UrlFormat = Experimentals.Extensions_Url)]

src/ModelContextProtocol.Core/Protocol/ServerCapabilities.cs

@@ -104,8 +104,7 @@ public McpTasksCapability? Tasks
     /// </para>
     /// <para>
     /// Extensions provide a framework for extending the Model Context Protocol while maintaining
-    /// interoperability. Both clients and servers advertise extension support via this field during
-    /// the initialization handshake.
+    /// interoperability. Servers advertise extension support via this field during the initialization handshake.
     /// </para>
     /// </remarks>
     [Experimental(Experimentals.Extensions_DiagnosticId, UrlFormat = Experimentals.Extensions_Url)]