bug#21747: 25.0.50; while-no-input breaks kbd event handling when called from post-command-hook

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sun, 25 Oct 2015 14:43:06 +0000
> From: Artur Malabarba <bruce.connor.am@gmail.com>
> Cc: Tassilo Horn <tsdh@gnu.org>, Stefan Monnier <monnier@iro.umontreal.ca>, Kim Storm <storm@cua.dk>, 
> 	21747@debbugs.gnu.org
> 
> I've extended the docstring.

Thanks.

> +otherwise the error might happen repeatedly and make Emacs nonfunctional.
> +
> +It is usually a bad idea to use this hook for expensive processing.
> +If unavoidable, `while-no-input' can be used avoid making Emacs
                                              ^^^
"to" is missing where indicated.

> +unresponsive while the user types.  Furthermore, this hook is run
> +before redisplay, so the effect of the executed command won't be
> +displayed on the buffer until after the hook has finished (giving the
> +impression that Emacs is hanging).  You can call `redisplay' inside
> +`while-no-input' to avoid this.

Perhaps only the 1st sentence or 2 sentences should be left in the doc
string, and the rest moved to the ELisp manual?  It seems too long and
detailed for a doc string.