ci: Add test for building docs

.github/workflows/test-docs.yml

@@ -0,0 +1,39 @@
+name: test-docs
+on:
+  workflow_dispatch:
+  pull_request:
+
+jobs:
+  pre_job:
+    runs-on: ubuntu-latest
+    outputs:
+      should_skip: ${{ steps.skip_check.outputs.should_skip }}
+    steps:
+      - id: skip_check
+        uses: fkirc/skip-duplicate-actions@master
+        with:
+          skip_after_successful_duplicate: "true"
+          paths: '["docs/**", ".github/workflows/docs.yml"]'
+          do_not_skip: '["workflow_dispatch"]'
+
+  test-build-documentation:
+    name: Test building docs
+    needs: pre_job
+    if: ${{ needs.pre_job.outputs.should_skip != 'true' }}
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+
+      - uses: actions/setup-python@v2
+        with:
+          python-version: 3.x
+
+      - name: Install Python dependencies
+        run: pip install -r docs/requirements.txt
+
+      - name: Build docs with mkdocs
+        run: |
+          cd docs
+          mkdocs build