create Page Not Found service

Reviewed-by: Gode, Sebastian <sebastian.gode@t-systems.com>
Co-authored-by: tischrei <tino.schreiber@t-systems.com>
Co-committed-by: tischrei <tino.schreiber@t-systems.com>

otc_metadata/data/services/notfound.yaml

@@ -0,0 +1,13 @@
+---
+environment: hidden
+repositories:
+- environment: public
+  repo: opentelekomcloud-docs/page-not-found
+  type: github
+service_category: other
+service_title: Page Not Found
+service_type: pagenotfound
+service_uri: page-not-found
+teams:
+- name: docs-eco-rw
+  permission: write