Add helm-docs generation and linting

Generate docs for each chart and verify the committed docs match the
generated docs.

Signed-off-by: Daniel Farrell <dfarrell@redhat.com>

.github/workflows/linting.yml

@@ -39,6 +39,29 @@ jobs:
       - name: Run gitlint
         run: make gitlint
 
+  helm-docs:
+    name: Helm Docs Generation
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out the repository
+        uses: actions/checkout@v2
+
+      - name: Run helm-docs and verify docs are up-to-date
+        run: |
+          HELM_DOCS_VERSION="0.15.0"
+          # Avoid polluting repo with helm-docs' README/LICENSE or other files in the release archive
+          cd /tmp
+          curl -sL "https://github.com/norwoodj/helm-docs/releases/download/v${HELM_DOCS_VERSION}/helm-docs_${HELM_DOCS_VERSION}_Linux_x86_64.tar.gz" | tar zx
+          cd -
+          /tmp/helm-docs
+          if [[ ! -z "$(git status --porcelain)" ]]; then
+            echo "Helm docs not up-to-date:"
+            git status --porcelain
+            git diff
+            echo "Run helm-docs, as the CI does above, and commit the updated docs."
+            exit 1
+          fi
+
   markdown-link-check:
     name: Markdown Links (modified files)
     runs-on: ubuntu-latest