howto/setup-git-server-over-http: fix unescaped '^'s

The text contains two 'grep' invocations which include the 'start
of line' regular expression character '^'. Asciidoc mis-interprets
this use of '^' as a superscript request. In order to fix this
formatting problem, use backticks (`) to quote the text of the
affected 'grep' command invocations.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>

Documentation/howto/setup-git-server-over-http.txt

@@ -81,8 +81,8 @@ Initialize a bare repository
     $ git --bare init
 
 
-Change the ownership to your web-server's credentials. Use "grep ^User
-httpd.conf" and "grep ^Group httpd.conf" to find out:
+Change the ownership to your web-server's credentials. Use `"grep ^User
+httpd.conf"` and `"grep ^Group httpd.conf"` to find out:
 
     $ chown -R www.www .