Fix and enhance documentation of TcpListener::accept()

[JanZerebecki]

No description provided.

[carllerche]

Thanks for the PR. The docs are definitely out of date.

I would suggest instead of Err(would_block()), maybe Err(e) where e is an io::Error of kind WouldBlock?

Also, I would suggest removing this May block if there is nothing ready to be accepted. as it isn't true (since the socket is in non-blocking mode).

[JanZerebecki]

Right, I looked at the wrong place for the call making it non-blocking. I adopted your suggestions and clarified a bit more.

[carllerche]

Thanks, merged: 9792b74