remove logical typo in documentation of sample update hook

Signed-off-by: Heiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/githooks.txt

diff --git a/Documentation/githooks.txt b/Documentation/githooks.txt
index 79f633e..06e0f31 100644
--- a/Documentation/githooks.txt
+++ b/Documentation/githooks.txt
@@ -245,7 +245,7 @@
 for the user.
 
 The default 'update' hook, when enabled--and with
-`hooks.allowunannotated` config option turned on--prevents
+`hooks.allowunannotated` config option unset or set to false--prevents
 unannotated tags to be pushed.
 
 [[post-receive]]