bug#33191: 26.1.50; remove remaining process input batching doc

[Eli Zaretskii]

> Date: Sun, 09 Dec 2018 11:45:26 +0100
> From: charles@aurox.ch (Charles A. Roelli)
> Cc: 33191@debbugs.gnu.org
> 
> > Date: Sun, 28 Oct 2018 20:52:34 +0100
> > From: charles@aurox.ch (Charles A. Roelli)
> > 
> > (as discussed in Bug#33050#116)
> > 
> > - Remove mention of "stray character injections" in Elisp node
> >   "Asynchronous Processes".
> > - Remove doc of "process-send-string" and "process-send-region" 
> >   claiming to split process input every 500 characters.
> 
> Here's a suggested change for emacs-26:

Thanks, but this removes too much, IMO.  The 500 bytes figure should
go away, but we still send the string in chunks, albeit
system-dependent ones, and we still allow output from processes to
arrive between chunks.