docs: add up to date documentation for AsyncWrap

[AndreasMadsen]

This should be an up to date documentation on the AsyncWrap API. I have not included in discussion on the future of the API, but there a small section (Things you might not expect) on some stuff that other users should know.

Also I'm not really sure what the purpose of the provider argument is and how it compares to this.constructor.name someone else should elaborate on that.

PS: I've heard my spelling isn't ideal, bear with me.

[pmuellr]

@trevnorris can you review?

[trevnorris]

@AndreasMadsen Thanks for all the text. I think my referenced patch is the last for the near future. There are some grammatical things, but we'll worry about those later.

[AndreasMadsen]

@trevnorris Thanks for the review. I have updated the documentation based on your comments and nodejs/node#3216 (add parent object).

[AndreasMadsen]

Thanks @Qard, I have updated the documentation.

[pmuellr]

I assume we're ready to merge this? Or are more updates coming?

[trevnorris]

finished another round. mainly grammer and stuff. great stuff.

[AndreasMadsen]

Thanks @trevnorris.

[trevnorris]

Two nits. Other than that I would say LGTM. Nice bit of writing you did!

[AndreasMadsen]

Fixed.

[AndreasMadsen]

@Qard@pmuellr Any last comments?

[Qard]

LGTM