Add registration key documentation #314
Description
[DO ONLY WHEN 0.56.0 is released]
We have a new concept of instance registration key.
When providing those to an instance (either with --registration-key or CAIDO_REGISTRATION_KEY env var) it will ensure that the client is registered automatically within a given workspace.
Why is this necessary?
If you don't pass this key, the instance is available to anybody until somebody claims it to themselves. This is not acceptable for businesses than want to deploy a lot of instances in advance for testers ahead of an engagement or on demand for a retest.
Also in the next few weeks we will create the concept of "service accounts"/"bot users" that will be able to log into caido without doing the flow in the dashboard. This will allow us to run caido in github actions and other environments without human intervention. Obviously the registration token make sense in that case since the "service account" needs to have an instance already all setup before it can auth.
Additional documentation
It would also be good to document the lifecycle a Caido instance from start to delete. So when you start it, it creates an oauth2 client for itself automatically, then it remains "unclaimed" until a user claims it (meaning anybody with access to it can connect and claim it, this is potentially dangerous state to stay in), then is lives happy and can auth users.
We should link it to the concepts workspaces (do we have documentation on that?). Instances live in workspaces and registration keys tie a new instance to a workspace.
