Update description on no-string-refs

[danielbeutner]

Hi,

the example given in your description is colliding with no-return-assign. A solution to this is mentioned in airbnb/javascript#884.

You can use replace

render() {
  return <div ref={c => this.hello = c}>Hello, world.</div>;
}

with

render() {
  return <div ref={(c) => { this.hello = c; }}>Hello, world.</div>;
}

Best, Daniel