Identify which parts of our doc are still inherited from Incognito

Before 1.0, it would be worth parsing through all the Documentation section, and:

- Identify which parts are still from Incognito and should be rewritten.

- Delete parts that don’t apply anymore.

- Probably spot out parts that are outdated.
- Create ticket for things that cannot be done straight away.

Parent Task: #5977 (closed)

Original created by @sajolida on 6868 (Redmine)