Documentation: complicate example of "man git-command"

The manual page for the command invoked as "git clone" is named
git-clone(1), and similarly for the rest of the git commands.
Make sure our first example of this in tutorials makes it clear
that it is the first two words of a command line that make up the
command's name (that is: for example, the effect of "git svn
dcommit" is described in git-svn(1)).

Signed-off-by: Jonathan Nieder <jrnieder@uchicago.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/gittutorial.txt

@@ -20,10 +20,10 @@ for example, to test the latest version, you may prefer to start with
 the first two chapters of link:user-manual.html[The Git User's Manual].
 
 First, note that you can get documentation for a command such as "git
-diff" with:
+log --graph" with:
 
 ------------------------------------------------
-$ man git-diff
+$ man git-log
 ------------------------------------------------
 
 It is a good idea to introduce yourself to git with your name and

Documentation/user-manual.txt

@@ -18,7 +18,7 @@ People needing to do actual development will also want to read
 Further chapters cover more specialized topics.
 
 Comprehensive reference documentation is available through the man
-pages.  For a command such as "git clone", just use
+pages.  For a command such as "git clone <repo>", just use
 
 ------------------------------------------------
 $ man git-clone