doc: add note about removeListener order

doc/api/events.md

@@ -581,6 +581,26 @@ being removed. This will not impact the order in which listeners are called,
 but it means that any copies of the listener array as returned by
 the `emitter.listeners()` method will need to be recreated.
 
+When a single function has been added as a handler multiple times for a single
+event (as in the example below), `removeListener()` will remove the most
+recently added instance. In the example the `once('ping')`
+listener is removed:
+
+```js
+const ee = new EventEmitter();
+
+function pong() {
+  console.log('pong');
+}
+
+ee.on('ping', pong);
+ee.once('ping', pong);
+ee.removeListener('ping', pong);
+
+ee.emit('ping');
+ee.emit('ping');
+```
+
 Returns a reference to the `EventEmitter`, so that calls can be chained.
 
 ### emitter.setMaxListeners(n)