bug#13791: 24.3.50; scroll-margin docstring says "recenter"

[Eli Zaretskii]

> From: Dmitry Gutov <dgutov@yandex.ru>
> Date: Sat, 23 Feb 2013 04:21:24 +0400
> 
> The docstring says: "Recenter the window whenever point gets within this
> many lines of the top or bottom of the window."
> 
> That's not entirely accurate. Depending on the value of
> `scroll-conservatively', the window may get scrolled instead.

That's true.  However, how to describe this in a manner that will not
confuse the reader is less clear.  "Recenter or scroll" is not very
useful, IMO, as it doesn't say which will happen.  Suggestions are
welcome.