Add some basic unittests for metadata sanity

Reviewed-by: Hasko, Vladimir <vladimir.hasko@t-systems.com>
Co-authored-by: gtema <artem.goncharov@gmail.com>
Co-committed-by: gtema <artem.goncharov@gmail.com>

otc_metadata/data/services.yaml

@@ -1,3 +1,19 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# Please consult with otc_metadata.services.Services:_sort_data for expected
+# sort order. When unsure perform tools/sort_metadata.py for getting it sorted.
+---
 documents:
   - hc_location: api/antiddos
     html_location: docs/antiddos/api-ref
@@ -1035,6 +1051,8 @@ service_categories:
     title: Security Services
   - name: storage
     title: Storage
+  - name: other
+    title: Other
 services:
   - repositories:
       - environment: internal