git-am.txt is no stub anymore

That notice was added by me for the emergency documentation, but Junio
already expanded it to a full-fledged manual page. This patch removes
the notice.

Signed-off-by: Petr Baudis <pasky@suse.cz>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-am.txt

@@ -82,8 +82,6 @@ Documentation
 --------------
 Documentation by Petr Baudis, Junio C Hamano and the git-list <git@vger.kernel.org>.
 
-This manual page is a stub. You can help the git documentation by expanding it.
-
 GIT
 ---
 Part of the gitlink:git[7] suite