docs: fix automated docs generation

New version of material theme and plugins breaks when there is empty
"tags" stanza in the metadata section of the markdown. This patch only
adds "tags" if there are any to add.

Second issue fixed is adding an empty tags.md file which is now required
to present collected tags in the generated docs.

Signed-off-by: Milosz Wasilewski <milosz.wasilewski@foundries.io>

Author: mwasilew

docs/tags.md

@@ -0,0 +1,3 @@
+# Tags
+
+<!-- material/tags -->

mkdocs.yml

@@ -11,7 +11,8 @@ plugins:
             - 'automated/linux'
             - 'automated/android'
             - 'manual'
-    - tags
+    - tags:
+        tags_file: tags.md
     - exclude:
         glob:
           - plans/*

mkdocs_plugin/testdefinitionsmkdocs/__init__.py

@@ -51,11 +51,11 @@ def generate_yaml_markdown(self, filename, config):
                 mdFile = mdutils.MdUtils(file_name=tmp_filename)
                 tags_section = "---\n"
                 tags_section += "title: %s\n" % metadata["name"]
-                tags_section += "tags:\n"
                 scope_list = metadata.get("scope", [])
                 os_list = metadata.get("os", [])
                 device_list = metadata.get("devices", [])
-                if scope_list is not None:
+                if scope_list:
+                    tags_section += "tags:\n"
                     for item in scope_list:
                         tags_section += " - %s\n" % item
                 tags_section += "---\n"