fixed lack of '>' and  sample code ( core_manual_java.md )

Fixed docs ( core manual java )

I fixed two points of core_manual_java.html

1) fixed lack of '>'
2) fixed sample code of "SockJS - EventBus Bridge > Setting up the Bridge"

  HttpServer server = vertx.createHttpServer();
  
  JsonObject config = new JsonObject().putString("prefix", "/echo");
  
  vertx.createSockJSServer(server).bridge(config, new JsonArray(), new JsonArray());
  
  server.listen(8080);

This code can not receive any events. So I changed that

  HttpServer server = vertx.createHttpServer();
  
  JsonObject config = new JsonObject().putString("prefix", "/eventbus");
  
  JsonArray noPermitted = new JsonArray();
  noPermitted.add(new JsonObject());
  
  vertx.createSockJSBridge(server).bridge(config, noPermitted, noPermitted);
  
  server.listen(8080);

And I moved some descriptions under this code.

One more things, I changed SockJSBridge's prefix "/echo" to "/eventbus".
Because of below sample code "Using the Event Bus from client side JavaScript" uses "/eventbus".