Hooks are poorly documented

[cortho]

WHAT Needs to be Documented?

• Hook prerequisites (type filesystem in info.xml)
• Symfony events

Obviously there already were tickets but they had been closed without any additional documentation. See

• https://github.com/owncloud/docs/issues/393
• https://github.com/owncloud/docs/issues/311

WHERE Does This Need To Be Documented (Link)?

most probably at https://doc.owncloud.com/server/next/developer_manual/app/fundamentals/hooks.html

WHY Should This Change Be Made?

Some hooks/requirements are not documented at all.

(Optional) What Type Of Content Change Is This?

• [x] New Content Addition
• [ ] Old Content Deprecation
• [ ] Existing Content Simplification
• [ ] Bug Fix to Existing Content

(Optional) Which Manual Does This Relate To?

• [ ] Admin Manual
• [x] Developer Manual
• [ ] User Manual
• [ ] Android
• [ ] iOS
• [ ] Branded Clients
• [ ] Desktop Client
• [ ] Other