PR Summary

• Update to Hooks documentation
  The Hooks.md file has been updated to include new hooks that help in filtering the content and abstracts of feeds in events.

• Addition of a document explaining the "gatherpress_event_feed_content" hook
  A new documentation file named gatherpress_event_feed_content.md has been added. This file explains the purpose and functionality of the gatherpress_event_feed_content hook, and it also provides examples of how to use it.

• Introduction of the "gatherpress_event_feed_excerpt" hook documentation
  Another new file, gatherpress_event_feed_excerpt.md has been added. This document briefly explains the functionalities of the gatherpress_event_feed_excerpt hook and provides example code, explaining how to utilize this hook.