.async gone (-> README.md documentation)

[axkibe]

I'm just updating package dependencies of a project and it fails due to .async gone.

From git history I assume it has just been renamed to .callback? Yes?

Suggestion update README.md ;-) (Maybe with a hint for a while that it used to be called .async.)

PS: I'm using this module since years for all my major node.js projects, thanks BTW.

PPS: --harmony-generators seems doesn't need to be specified anymore with recent node.js builds (I just upgraded to v9.2. I don't know where ES6 started to become fully enabled by default)