Clean-up and restructure

Also added PR check

.github/workflows/pr.yml

@@ -0,0 +1,19 @@
+name: Check PR
+
+on: pull_request
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout repo content
+        uses: actions/checkout@v2
+
+      - name: Setup Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: 3.8
+      
+      - name: Check permalinks
+        run: python .github/scripts/check_permalinks.py