Fix 'git help help'
Fix 'git help help'

git help foo invokes man git-foo if foo is a git command, otherwise it
invokes man gitfoo. 'help' is not a git command, but the manual page is
called git-help, so add this special exception.

Signed-off-by: Miklos Vajna <16f13092e03e3d9e997de904d0f86cc803fb6ef7@frugalware.org>
Acked-by: Christian Couder <ddbaab5867ed34fd53535b58c9cdd59abd2e2aff@tuxfamily.org>
Signed-off-by: Junio C Hamano <a6723cc3f76163bf7adb636a73ac3b0ceb3e6b9b@pobox.com>

destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git,destenson/git