Add xml comments to HubInvocationContext (#11683)

Author: BrennanConroy

src/SignalR/server/Core/src/HubInvocationContext.cs

@@ -2,20 +2,41 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System.Collections.Generic;
+using Microsoft.AspNetCore.Authorization;
 
 namespace Microsoft.AspNetCore.SignalR
 {
+    /// <summary>
+    /// Context for a Hub invocation.
+    /// </summary>
     public class HubInvocationContext
     {
+        /// <summary>
+        /// Instantiates a new instance of the <see cref="HubInvocationContext"/> class.
+        /// </summary>
+        /// <param name="context">Context for the active Hub connection and caller.</param>
+        /// <param name="hubMethodName">The name of the Hub method being invoked.</param>
+        /// <param name="hubMethodArguments">The arguments provided by the client.</param>
         public HubInvocationContext(HubCallerContext context, string hubMethodName, object[] hubMethodArguments)
         {
             HubMethodName = hubMethodName;
             HubMethodArguments = hubMethodArguments;
             Context = context;
         }
 
+        /// <summary>
+        /// Gets the context for the active Hub connection and caller.
+        /// </summary>
         public HubCallerContext Context { get; }
+
+        /// <summary>
+        /// Gets the name of the Hub method being invoked.
+        /// </summary>
         public string HubMethodName { get; }
+
+        /// <summary>
+        /// Gets the arguments provided by the client.
+        /// </summary>
         public IReadOnlyList<object> HubMethodArguments { get; }
     }
 }