Re: file-name-as-directory: Update doc. string

[Eli Zaretskii]

> From: Tino Calancha <address@hidden>
> Date: Mon, 12 Sep 2016 16:04:09 +0900 (JST)
> Cc: address@hidden
> 
> Doc. string for `file-name-as-directory' is out of date; this
> doc. string suggests that expand-file-name only accepts
> a directory name as its second argument.  It is explicitely
> mentioned in expand-file-name doc. string that the second
> argument can be a directory file name as well.

But that doesn't invalidate what this doc string says, does it?  So
I'm not sure we should remove that sentence.

Thanks.