add github ci

.github/workflows/mkdocs.yml

@@ -0,0 +1,20 @@
+name: mkdocs
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron:  '0 12 * * *' # Every day noon UTC
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v4
+
+    - name: install mkdocs
+      run: pip3 install mkdocs==0.17.5
+
+    - name: build
+      run: make