Update comment as suggested

Co-Authored-By: Stephen Toub <stoub@microsoft.com>

src/libraries/System.Net.Sockets/src/System/Net/Sockets/SocketAsyncContext.Unix.cs

@@ -279,7 +279,7 @@ public void Dispatch(bool processAsyncOperationSynchronously)
                 }
                 else
                 {
-                    // Async operation.  Process the IO and callback on the threadpool.
+                    // Async operation.  Process the IO and callback asynchronously on the threadpool (even if we're already on a pool thread).
                     ThreadPool.UnsafeQueueUserWorkItem(this, preferLocal: false);
                 }
             }