Document page draft management handling and controls

[ssddanbrown]

Right now it's not too clear on how to manage/clear drafts, and the behaviour BookStack uses for this system.
There's perhaps a UX task to make things more obvious within-app, but either way it would be good to have this kind of thing documented.

[mitchell-accipio]

This is something I have noticed; I would be happy to create this documentation, but would need a briefing on how the drafts work and how to clear them, since I haven't yet had to do it.

If it's a case of it being faster for you to do it yourself than to explain it to me then that's understandable, but consider the offer open