fix(backstage-doc): added missing main mkdocs.yaml

mkdocs.yaml

@@ -0,0 +1,22 @@
+site_name: eDFDoc
+site_description: 'eDF PoC documentation'
+
+nav:
+  - Getting Started: 
+    - User Documentation: 'gettingstarted/user-documentation.md'
+  - User Guide: 
+    - OpenBAO: 'userguide/openbao.md'
+    - CI Workflow: 'userguide/ci-workflow.md'
+  - Technical Documentation:
+    - Architecture: 'techdocs/architecture.md'
+    - Deployment: 'techdocs/deployment.md'
+    - Development: 'techdocs/development.md'
+    - Testing: 'techdocs/testing.md'
+  - About: 
+    - License: about/license.md
+    - Release Notes: about/release-notes.md
+    - A Test doc: about/mkdocs-test.md
+
+
+plugins:
+  - techdocs-core