Fix typo in ManagedWebSocket comment

src/libraries/Common/src/System/Net/WebSockets/ManagedWebSocket.cs

@@ -709,7 +709,7 @@ private async ValueTask<TWebSocketReceiveResult> ReceiveAsyncPrivate<TWebSocketR
                             null, null);
                     }
 
-                    // Otherwise, read as much of the payload as we can efficiently, and upate the header to reflect how much data
+                    // Otherwise, read as much of the payload as we can efficiently, and update the header to reflect how much data
                     // remains for future reads.  We first need to copy any data that may be lingering in the receive buffer
                     // into the destination; then to minimize ReceiveAsync calls, we want to read as much as we can, stopping
                     // only when we've either read the whole message or when we've filled the payload buffer.