Fixed update-hook example allow-users format.

The example provided with the update-hook-example does not work on
either bash 2.05b.0(1)-release nor 3.1.17(1)-release. The matcher did
not match the lines that it advertised to match, such as:

refs/heads/bw/        linus
refs/heads/tmp/*      *

In POSIX 1003.2 regular expressions, the star (*), is not an wildcard
meaning "match everything", it matches 0 or more matches of the atom
preceding it.

So to match "refs/heads/bw/topic-branch", the matcher should be written
as "refs/heads/bw/.*" to match "refs/heads/bw/" and everything after it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/howto/update-hook-example.txt

@@ -158,11 +158,11 @@ This uses two files, $GIT_DIR/info/allowed-users and
 allowed-groups, to describe which heads can be pushed into by
 whom.  The format of each file would look like this:
 
-	refs/heads/master	junio
+        refs/heads/master	junio
         refs/heads/cogito$	pasky
-	refs/heads/bw/		linus
-        refs/heads/tmp/		*
-        refs/tags/v[0-9]*	junio
+        refs/heads/bw/.*	linus
+        refs/heads/tmp/.*	.*
+        refs/tags/v[0-9].*	junio
 
 With this, Linus can push or create "bw/penguin" or "bw/zebra"
 or "bw/panda" branches, Pasky can do only "cogito", and JC can