am doc: add a pointer to relevant hooks
am doc: add a pointer to relevant hooks

It is not obvious when looking at a new command what hooks will affect
it.  Add a HOOKS section to the git-am(1) page, imitating
git-commit(1), to make it easier for people to discover e.g. the
applypatch-msg hook that can implement a custom subject-mangling
strategy (e.g., removing a "bug #nnnn:" prefix introduced by a bug
tracker).

Reported-by: Phillip Susi <14eed9370c6d903f3941abaf81fa333fd2827778@ubuntu.com>
Signed-off-by: Jonathan Nieder <b57189c5f2fd5b3daf3350a77fde90def1080fa5@gmail.com>
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