Update README.md

Author: chris-smith

README.md

@@ -61,7 +61,22 @@ const AddTwoInts = rosnodejs.require('beginner_tutorials').srv.AddTwoInts;
 const service = nh.advertiseService('/add_two_ints', AddTwoInts, (req, resp) => { ... });
 const client = nh.serviceClient('/add_two_ints', AddTwoInts);
 ```
+## Actions (Experimental)
+```
+const nh = rosnodejs.nh;
+const as = new rosnodejs.ActionServer({
+  nh,
+  type: 'turtle_actionlib/ShapeAction',
+  actionServer: '/turtle_shape'
+});
 
+as.on('goal, function (goal) {
+  goal.setAccepted();
+});
+
+const ac = nh.actionClientInterface('/turtle_shape, 'turtle_actionlib/ShapeAction');
+ac.sendGoal({ goal: {edges: 3, radius: 1}});
+```
 ## Run the turtlesim example
 
 Start: