Publish (initial version of) our glossary

Pls review the glossary: 12_glossary.md · glossary · Föderale IT-Kooperation (FITKO) / Matrix-based G2X communication („Neo“) / Solution architecture · GitLab

See draft.

AC

• Move the draft into the existing MR.
• Glossary is sorted alphabetically.
• MR is reviewed and merged.