* docs: Restructure and improve DNS documentation
Reorganizes DNS docs into overview, configuration, settings, and troubleshooting
guides with clearer explanations and UI-aligned terminology
* amendments from Vik's feedback
* clarified IP assignment range
* remove incorrect common mistake note
* - added diagrams
- renamed dns overview.mdx to index.mdx
- updated references/redirects
- created new spacer div class
---------
Co-authored-by: Ashley Mensah <ashley@netbird.io>
