Update hooks.md

added additional hooks in hook.md. on_trash, on_change and after_delete.

frappe/docs/user/en/guides/basics/hooks.md

@@ -226,6 +226,9 @@ The hook function will be passed the doc in concern as the only argument.
 * `on_submit`
 * `on_cancel`
 * `on_update_after_submit`
+* `on_change`
+* `on_trash`
+* `after_delete`
 
 
 Eg,