Boarding documentation

[Janik-Haag]

Is your feature request related to a problem? Please describe.

There is a few things that need to be done when a board-(member/observer) joins or leaves the board and we should document the process.

Describe the solution you'd like

Add a document like https://github.com/NixOS/moderation/blob/main/boarding.md

Additional context

A few things I can think of are:

• GitHub foundation repo permissions (at least triage permissions for board observers would be nice)
• Notion acces
• Open collective
• BitWarden
• Email (improvmx)
• Matrix rooms
• Calendar (currently google calendar)
• Current Meetings/Events (bi-weekly board meeting)
• KVK filings for board member
• Banking/Payment things?

and probably a few more I forgot?