Create a README.md for the organization to introduce Metafacture

[TobiasNx]

If stumbling over the organization of metafacture, one has no clue where to start.
Therefore I would suggest we introduce a README.md for the organization that helps you navigate through the repos.

[TobiasNx]

Documentation for organization readmes: https://docs.github.com/en/organizations/collaborating-with-groups-in-organizations/customizing-your-organizations-profile