manpages: use teletype font for sample command lines

I think that some of these uses of italics were meant to be
rendered in quotation marks, anyway.

Signed-off-by: Jonathan Nieder <jrnieder@uchicago.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 07e9e57..adc027c 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -136,8 +136,8 @@
 +
 Other options are available to control how the manual page is
 displayed. See linkgit:git-help[1] for more information,
-because 'git --help ...' is converted internally into 'git
-help ...'.
+because `git --help ...` is converted internally into `git
+help ...`.
 
 --exec-path::
 	Path to wherever your core git programs are installed.