Enable Enterprise Dashboard Alerting document to be publicly available (#65)

Reviewed-on: #65
Reviewed-by: Gode, Sebastian <sebastian.gode@t-systems.com>
Co-authored-by: Tino Schreiber <tino.schreiber@t-systems.com>
Co-committed-by: Tino Schreiber <tino.schreiber@t-systems.com>

otc_metadata/data/documents/ed-alerting.yaml

@@ -6,6 +6,6 @@ title: Alerting
 type: alerting
 cloud_environments:
   - name: eu_de
-    visibility: hidden
-    pdf_visibility: hidden
+    visibility: public
+    pdf_visibility: public
     pdf_enabled: true