Fix some links in markdown docs
Links with file extension can be accessed via GitLab UI and will be automatically converted by Docusaurus.
E.g.
- [Zustellberechtigungs-Scopes](./scopes)
+ [Zustellberechtigungs-Scopes](./scopes.md)Links with file extension can be accessed via GitLab UI and will be automatically converted by Docusaurus.
E.g.
- [Zustellberechtigungs-Scopes](./scopes)
+ [Zustellberechtigungs-Scopes](./scopes.md)