ci(docs): Add rules for linting job

docs/.gitlab-ci.yaml

@@ -3,8 +3,17 @@ stages:
 
 lint-docs:
   extends: .earthly
+  stage: lint
   script:
     - earthly --ci +docs-lint
+  rules:
+    - if: '$FORCE_DOCS_BUILD == "true"'
+    - if: '$CI_COMMIT_BRANCH == $CI_DEFAULT_BRANCH && $CI_PIPELINE_SOURCE == "push"'
+      changes:
+        paths:
+          - docs/**/*
+          - images/**/README.md
+          - charts/**/README.md
 
 build-docs:
   stage: build