ci: add link checker, README convention check and PR templat

.github/workflows/markdown-lint.yml

@@ -0,0 +1,33 @@
+name: Markdown lint
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+permissions:
+  contents: read
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  markdownlint:
+    name: Markdown lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: DavidAnson/markdownlint-cli2-action@v19
+        with:
+          globs: "**/*.md"
+
+  readme-conventions:
+    name: README conventions
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Check entry format and duplicates
+        run: python3 .github/scripts/check_readme.py