fixes typo in the rpc example

rpc.helloWorld(1,2,3, function(response){
        // here we can do something with the return value from `helloWorld`
    }, function(errorObj){
        // here we can react to a possible error
    }; <== forgot to close the parenthesis

README.md

@@ -133,7 +133,7 @@ Call the methods like this
         // here we can do something with the return value from `helloWorld`
     }, function(errorObj){
         // here we can react to a possible error
-    };
+    });
 ```
 
 And this is what's needed for the *provider*