Update dependabot.yml

.github/dependabot.yml

@@ -1,5 +1,8 @@
+# See help here: https://docs.github.com/en/free-pro-team@latest/github/administering-a-repository/enabling-and-disabling-version-updates
+
 version: 2
 updates:
+  # Enable version updates for nGraph Python API
   - package-ecosystem: pip
     directory: "/ngraph/python"
     schedule:
@@ -10,4 +13,5 @@ updates:
     reviewers:
       - postrational
     labels:
-  - dependencies
+      - "category: dependencies"
+