Merge branch 'ab/config-based-hooks-2'

More "config-based hooks".

* ab/config-based-hooks-2:
  run-command: remove old run_hook_{le,ve}() hook API
  receive-pack: convert push-to-checkout hook to hook.h
  read-cache: convert post-index-change to use hook.h
  commit: convert {pre-commit,prepare-commit-msg} hook to hook.h
  git-p4: use 'git hook' to run hooks
  send-email: use 'git hook run' for 'sendemail-validate'
  git hook run: add an --ignore-missing flag
  hooks: convert worktree 'post-checkout' hook to hook library
  hooks: convert non-worktree 'post-checkout' hook to hook library
  merge: convert post-merge to use hook.h
  am: convert applypatch-msg to use hook.h
  rebase: convert pre-rebase to use hook.h
  hook API: add a run_hooks_l() wrapper
  am: convert {pre,post}-applypatch to use hook.h
  gc: use hook library for pre-auto-gc hook
  hook API: add a run_hooks() wrapper
  hook: add 'run' subcommand

Documentation/git-hook.txt

@@ -0,0 +1,45 @@
+git-hook(1)
+===========
+
+NAME
+----
+git-hook - Run git hooks
+
+SYNOPSIS
+--------
+[verse]
+'git hook' run [--ignore-missing] <hook-name> [-- <hook-args>]
+
+DESCRIPTION
+-----------
+
+A command interface to running git hooks (see linkgit:githooks[5]),
+for use by other scripted git commands.
+
+SUBCOMMANDS
+-----------
+
+run::
+	Run the `<hook-name>` hook. See linkgit:githooks[5] for
+	supported hook names.
++
+
+Any positional arguments to the hook should be passed after a
+mandatory `--` (or `--end-of-options`, see linkgit:gitcli[7]). See
+linkgit:githooks[5] for arguments hooks might expect (if any).
+
+OPTIONS
+-------
+
+--ignore-missing::
+	Ignore any missing hook by quietly returning zero. Used for
+	tools that want to do a blind one-shot run of a hook that may
+	or may not be present.
+
+SEE ALSO
+--------
+linkgit:githooks[5]
+
+GIT
+---
+Part of the linkgit:git[1] suite

Documentation/githooks.txt

@@ -698,6 +698,10 @@ and "0" meaning they were not.
 Only one parameter should be set to "1" when the hook runs.  The hook
 running passing "1", "1" should not be possible.
 
+SEE ALSO
+--------
+linkgit:git-hook[1]
+
 GIT
 ---
 Part of the linkgit:git[1] suite