refactor(readme): add hint to docs root, in case pages are down

README.md

@@ -4,3 +4,8 @@ This is the repository of the unified-ticketing library.
 
 Documentation for this is done with GitLab Pages using MkDocs and is available here:  
 https://transfer.hft-stuttgart.de/pages/unified-ticketing/
+
+If you don't want to open the Webpage or it is not available for whatever reason,
+the documentation root is in [docs/index.md][docs-root]
+
+[docs-root]: docs/index.md