bug#22023: 25.0.50; doc string of `eval-buffer'

[Eli Zaretskii]

> Date: Thu, 26 Nov 2015 16:12:49 -0800 (PST)
> From: Drew Adams <drew.adams@oracle.com>
> 
> The doc string suggests that the entire buffer is always evaluated,
> which is wrong.
> 
> The Elisp manual, node `Eval' is better.  It says that it operates on
> the entire _accessible portion_ of the buffer.  That's a big difference.
> 
> This function is commonly used by users, as a command.  They should
> realize that they can easily limit its scope by narrowing the buffer.
> 
> Even the treatment in the manual could be improved by making clear what
> is meant by the "accessible" portion of the buffer.  When the Emacs
> manual refers to the "accessible portion" it follows that phrase with
> this: (*note Narrowing::).  That makes everything clear.

Thanks, fixed.