fix(docs): contributions contents

[mfranzke]

Proposed changes

Some URLs we're pointing to another repository

• check for further relevant file types out of https://gitattributes.io/api/visualstudiocode%2Cweb%2Cmarkdown, but read through https://rehansaeed.com/gitattributes-best-practices/ first of all

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (fix on existing components or architectural decisions)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update (if none of the other choices apply)

Further comments

[github-actions]

🔭🐙🐈 Test this branch here: https://db-ui.github.io/mono/review/fix-docs-contributions-contents