[Feature]: Contexts guide for Plugin Authors

[lucasvienna]

Describe the feature

With the v0.3.0, Contexts have been introduced. It would be great if you could provide a quick write-up on best practices for when to emit new events or change the context between API calls, or even when new contexts might be required due to certain API calls closing the context.

Describe the implementation

A big comment on top of core/context.lua or something in the plugin example

[Tremolo4]

BetterBags_ItemRack kinda broke due to this, would appreciate some hints as to when to create contexts :)