add step to verify docs on area/documentation PRs (#1528)

* add step to verify docs on area/documentation PRs

* use GH actions to run the verification

* add check if label is set to area/documentation

* fix broken links in docs with WIP files

* add generating API docs before verifying

Signed-off-by: Sebastian Malton <sebastian@malton.name>

.github/workflows/check-docs.yml

@@ -0,0 +1,47 @@
+name: Publish docs via GitHub Pages
+on:
+  - pull_request
+jobs:
+  build:
+    name: Check Docs
+    runs-on: ubuntu-latest
+    if: github.event.label.name != 'area/documentation'
+    strategy:
+      matrix:
+        node-version: [12.x]
+    steps:
+      - name: Set up Python 3.7
+        uses: actions/setup-python@v2
+        with:
+          python-version: '3.x'
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install git+https://${{ secrets.GH_TOKEN }}@github.com/lensapp/mkdocs-material-insiders.git
+          pip install mike
+
+
+      - name: Checkout Release from lens
+        uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - name: git config
+        run: |
+           git config --local user.email "action@github.com"
+           git config --local user.name "GitHub Action"
+
+      - name: Using Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v1
+        with:
+          node-version: ${{ matrix.node-version }}
+
+      - name: Generate Extensions API Reference using typedocs
+        run: |
+           yarn install
+           yarn typedocs-extensions-api
+
+      - name: Verify that the markdown is valid
+        run: |
+          yarn run verify-docs