Documentation: format full commands in typewriter font

Use `code snippet` style instead of 'emphasis' for `git cmd ...`
according to the following rules:

* The SYNOPSIS sections are left untouched.

* If the intent is that the user type the command exactly as given, it
  is `code`.
  If the user is only loosely referred to a command and/or option, it
  remains 'emphasised'.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
diff --git a/Documentation/git-stash.txt b/Documentation/git-stash.txt
index 3f14b72..f001d0e 100644
--- a/Documentation/git-stash.txt
+++ b/Documentation/git-stash.txt
@@ -20,7 +20,7 @@
 DESCRIPTION
 -----------
 
-Use 'git stash' when you want to record the current state of the
+Use `git stash` when you want to record the current state of the
 working directory and the index, but want to go back to a clean
 working directory.  The command saves your local modifications away
 and reverts the working directory to match the `HEAD` commit.