README: remove outdated secureEndpoint reference

No longer needed with node-agent-base v2!

README.md

@@ -73,10 +73,6 @@ console.log('attempting to connect to WebSocket %j', endpoint);
 // create an instance of the `HttpsProxyAgent` class with the proxy server information
 var opts = url.parse(proxy);
 
-// IMPORTANT! Set the `secureEndpoint` option to `false` when connecting
-//            over "ws://", but `true` when connecting over "wss://"
-opts.secureEndpoint = parsed.protocol ? parsed.protocol == 'wss:' : false;
-
 var agent = new HttpsProxyAgent(opts);
 
 // finally, initiate the WebSocket connection