Publish RE methodolgy and results in arc42 repo

Problem

Right now the requirements and our RE methodology are only available in Nextcloud. To fullfill the open source requirement we want to publish the RE methodology, but we don't have a concrete spot and a method to do so, yet.

• We produced a text file explaining our RE solution approach.
• This needs to be reviewed and published in openCode.

Goal

Publish the requirements methodology on openCode.

Out-of-scope: Publishing the requirements themselves.

ACs

• Review following document: https://nextcloud.fitko.de/f/2132349
• Publish the above shared document in a separate 13_methodology.md chapter of our arc42 documentation.
• Chapter 13_methodology.md is listed in the README

Notes/ resources

additional info that is helpful when working on the ticket images, Figma, docs, etc

Who needs to be involved / informed

• reviewers:
• involved: @gerbauld
• informed: