Clarify that git-update-server-info should be run for every git-push

The old text suggested that git-update-server-info only needs to be run
if new tags or branches are created, but not for new commits.
Signed-off-by: NPavel Roskin <proski@gnu.org>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

Documentation/repository-layout.txt

@@ -133,14 +133,14 @@ info::
 	in this directory.
 
 info/refs::
-	This file is to help dumb transports to discover what
-	refs are available in this repository.  Whenever you
-	create/delete a new branch or a new tag, `git
-	update-server-info` should be run to keep this file
-	up-to-date if the repository is published for dumb
-	transports.  The `git-receive-pack` command, which is
-	run on a remote repository when you `git push` into it,
-	runs `hooks/update` hook to help you achieve this.
+	This file helps dumb transports discover what refs are
+	available in this repository.  If the repository is
+	published for dumb transports, this file should be
+	regenerated by `git update-server-info` every time a tag
+	or branch is created or modified.  This is normally done
+	from the `hooks/update` hook, which is run by the
+	`git-receive-pack` command when you `git push` into the
+	repository.
 
 info/grafts::
 	This file records fake commit ancestry information, to