Documentation: let asciidoc align related options

Command line options can share the same paragraph of description, if
they are related or synonymous. In these cases they should be written
among each other, so that asciidoc can format them itself.

Signed-off-by: Markus Heidelberg <markus.heidelberg@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-diff-files.txt

@@ -21,7 +21,10 @@ OPTIONS
 -------
 include::diff-options.txt[]
 
--1 -2 -3 or --base --ours --theirs, and -0::
+-1 --base::
+-2 --ours::
+-3 --theirs::
+-0::
 	Diff against the "base" version, "our branch" or "their
 	branch" respectively.  With these options, diffs for
 	merged entries are not shown.