[documentation] [task] Update hook_* documentation for 4.7

[drewish]

Issue status update for 
http://drupal.org/node/37019
Post a follow up: 
http://drupal.org/project/comments/add/37019

 Project:      Documentation
 Version:      <none>
 Component:    Developer Guide
 Category:     tasks
 Priority:     normal
 Assigned to:  drewish
 Reported by:  drewish
 Updated by:   drewish
 Status:       active

The following functions need documentation:
hook_form_alter()
hook_form_validate_alter()
hook_form_execute_alter()


Additionally, I've noticed that the following hook documentation needs
to be updated to use the new Forms API for 4.7:
hook_block()
hook_settings()
hook_user()


This isn't meant to be a complete list, just a starting point. Please
add any other hooks you may find.




drewish