Documentation: more examples.

Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-init-db.txt

@@ -40,9 +40,12 @@ Start a new git repository for an existing code base::
 +
 ----------------
 $ cd /path/to/my/codebase
-$ git-init-db
-----------------
+$ git-init-db <1>
+$ git-add . <2>
 
+<1> prepare /path/to/my/codebase/.git directory
+<2> add all existing file to the index
+----------------
 
 
 Author