Fix #1580 by correcting README sample (#1581)

Corrects the README sample in @aspnet/signalr-protocol-msgpack to use the proper UMD module name.

Author: analogrelay

client-ts/signalr-protocol-msgpack/README.md

@@ -16,7 +16,7 @@ To use the client in a browser, copy `*.js` files from the `dist/browser` folder
 
 ```JavaScript
 let connection = new signalR.HubConnection('/chat', {
-    protocol: new signalR.protocol.msgpack.MessagePackHubProtocol()
+    protocol: new signalR.protocols.msgpack.MessagePackHubProtocol()
 });
 
 connection.on('send', data => {
@@ -43,4 +43,4 @@ connection.on('send', data => {
 
 connection.start()
     .then(() => connection.invoke('send', 'Hello'));
-```
+```