Display hook description on the list.

Problem/Motivation

UX improvement, description of hook should be on list. it will be easier to find the hook we are looking for

example

/**
* Implements hook_post_update_NAME().
*
* Update the flag and unflag actions for existing flags.
*/
function flag_post_update_flag_actions() {}

Update the flag and unflag actions for existing flags. should be added somewhere in the list.