manpages: italicize nongit command names (if they are in teletype font)

Some manual pages use teletype font to set command names. We
change them to use italics, instead.  This creates a visual
distinction between names of commands and command lines that
can be typed at the command line. It is also more consistent
with other man pages outside Git.

In this patch, the commands named are non-git commands like bash.

Signed-off-by: Jonathan Nieder <jrnieder@uchicago.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git-merge-file.txt b/Documentation/git-merge-file.txt
index 6e70ea4..024ec01 100644
--- a/Documentation/git-merge-file.txt
+++ b/Documentation/git-merge-file.txt
@@ -39,8 +39,8 @@
 The exit value of this program is negative on error, and the number of
 conflicts otherwise. If the merge was clean, the exit value is 0.
 
-'git-merge-file' is designed to be a minimal clone of RCS `merge`; that is, it
-implements all of RCS merge's functionality which is needed by
+'git-merge-file' is designed to be a minimal clone of RCS 'merge'; that is, it
+implements all of RCS 'merge''s functionality which is needed by
 linkgit:git[1].