Update serverAddress documentation

Author: jozkee

src/Libraries/Microsoft.Extensions.AI.Abstractions/Tools/HostedMcpServerTool.cs

@@ -18,7 +18,7 @@ public class HostedMcpServerTool : AITool
     /// Initializes a new instance of the <see cref="HostedMcpServerTool"/> class.
     /// </summary>
     /// <param name="serverName">The name of the remote MCP server.</param>
-    /// <param name="serverAddress">The address of the remote MCP server.</param>
+    /// <param name="serverAddress">The address of the remote MCP server. This may be a URL, or in the case of a service providing built-in MCP servers with known names, it can be such a name.</param>
     /// <exception cref="ArgumentNullException"><paramref name="serverName"/> or <paramref name="serverAddress"/> is <see langword="null"/>.</exception>
     /// <exception cref="ArgumentException"><paramref name="serverName"/> or <paramref name="serverAddress"/> is empty or composed entirely of whitespace.</exception>
     public HostedMcpServerTool(string serverName, string serverAddress)