Add Websocket Example to README?

[SentryMan]

It's not immediately apparent how to configure and use WebSockets

[robaho]

I had figured the test case here was sufficient src/test/java/robaho/net/httpserver/websockets/WebSocketTest.java

[SentryMan]

Perhaps you should link to that test in the readme. To dig unguided through the tests to find an example may work for me, but it is a bit of friction I feel we could do without.