githooks.txt: put hooks into subsections

All hooks are currently in its own section. Which may confuse users,
because the section name serves as the hook file name and sections are
all caps for man pages. Putting them into a new HOOKS section and each
hook into a subsection keeps the case to lower case.

Signed-off-by: Bert Wesarg <bert.wesarg@googlemail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/githooks.txt

@@ -26,8 +26,11 @@ executable by default.
 
 This document describes the currently defined hooks.
 
+HOOKS
+-----
+
 applypatch-msg
---------------
+~~~~~~~~~~~~~~
 
 This hook is invoked by 'git-am' script.  It takes a single
 parameter, the name of the file that holds the proposed commit
@@ -43,7 +46,7 @@ The default 'applypatch-msg' hook, when enabled, runs the
 'commit-msg' hook, if the latter is enabled.
 
 pre-applypatch
---------------
+~~~~~~~~~~~~~~
 
 This hook is invoked by 'git-am'.  It takes no parameter, and is
 invoked after the patch is applied, but before a commit is made.
@@ -58,7 +61,7 @@ The default 'pre-applypatch' hook, when enabled, runs the
 'pre-commit' hook, if the latter is enabled.
 
 post-applypatch
----------------
+~~~~~~~~~~~~~~~
 
 This hook is invoked by 'git-am'.  It takes no parameter,
 and is invoked after the patch is applied and a commit is made.
@@ -67,7 +70,7 @@ This hook is meant primarily for notification, and cannot affect
 the outcome of 'git-am'.
 
 pre-commit
-----------
+~~~~~~~~~~
 
 This hook is invoked by 'git-commit', and can be bypassed
 with `\--no-verify` option.  It takes no parameter, and is
@@ -84,7 +87,7 @@ variable `GIT_EDITOR=:` if the command will not bring up an editor
 to modify the commit message.
 
 prepare-commit-msg
-------------------
+~~~~~~~~~~~~~~~~~~
 
 This hook is invoked by 'git-commit' right after preparing the
 default log message, and before the editor is started.
@@ -109,7 +112,7 @@ The sample `prepare-commit-msg` hook that comes with git comments
 out the `Conflicts:` part of a merge's commit message.
 
 commit-msg
-----------
+~~~~~~~~~~
 
 This hook is invoked by 'git-commit', and can be bypassed
 with `\--no-verify` option.  It takes a single parameter, the
@@ -126,7 +129,7 @@ The default 'commit-msg' hook, when enabled, detects duplicate
 "Signed-off-by" lines, and aborts the commit if one is found.
 
 post-commit
------------
+~~~~~~~~~~~
 
 This hook is invoked by 'git-commit'.  It takes no
 parameter, and is invoked after a commit is made.
@@ -135,14 +138,14 @@ This hook is meant primarily for notification, and cannot affect
 the outcome of 'git-commit'.
 
 pre-rebase
-----------
+~~~~~~~~~~
 
 This hook is called by 'git-rebase' and can be used to prevent a branch
 from getting rebased.
 
 
 post-checkout
------------
+~~~~~~~~~~~~~
 
 This hook is invoked when a 'git-checkout' is run after having updated the
 worktree.  The hook is given three parameters: the ref of the previous HEAD,
@@ -160,7 +163,7 @@ differences from the previous HEAD if different, or set working dir metadata
 properties.
 
 post-merge
------------
+~~~~~~~~~~
 
 This hook is invoked by 'git-merge', which happens when a 'git-pull'
 is done on a local repository.  The hook takes a single parameter, a status
@@ -175,7 +178,7 @@ for an example of how to do this.
 
 [[pre-receive]]
 pre-receive
------------
+~~~~~~~~~~~
 
 This hook is invoked by 'git-receive-pack' on the remote repository,
 which happens when a 'git-push' is done on a local repository.
@@ -204,7 +207,7 @@ for the user.
 
 [[update]]
 update
-------
+~~~~~~
 
 This hook is invoked by 'git-receive-pack' on the remote repository,
 which happens when a 'git-push' is done on a local repository.
@@ -247,7 +250,7 @@ unannotated tags to be pushed.
 
 [[post-receive]]
 post-receive
-------------
+~~~~~~~~~~~~
 
 This hook is invoked by 'git-receive-pack' on the remote repository,
 which happens when a 'git-push' is done on a local repository.
@@ -277,7 +280,7 @@ emails.
 
 [[post-update]]
 post-update
------------
+~~~~~~~~~~~
 
 This hook is invoked by 'git-receive-pack' on the remote repository,
 which happens when a 'git-push' is done on a local repository.
@@ -308,7 +311,7 @@ Both standard output and standard error output are forwarded to
 for the user.
 
 pre-auto-gc
------------
+~~~~~~~~~~~
 
 This hook is invoked by 'git-gc --auto'. It takes no parameter, and
 exiting with non-zero status from this script causes the 'git-gc --auto'