✏️ publish doc on actions

.github/workflows/gh-pages.yaml

@@ -0,0 +1,31 @@
+name: gh-pages
+
+on:
+  push:
+    branches:
+      - main
+      - '*'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ocaml/setup-ocaml@v2
+        with:
+          ocaml-compiler: 4.12.0
+      - name: Cache dependencies
+        uses: actions/cache@v2
+        with:
+          path: ~/.opam
+          key: ${{ runner.os }}-opam-${{ hashFiles('**/*.opam') }}
+          restore-keys: ${{ runner.os }}-opam-
+      - run: opam install . --deps-only --with-test
+      - run: opam install odoc
+      - run: opam exec -- dune build @doc
+      - name: Publish
+        uses: peaceiris/actions-gh-pages@v3
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+          publish_dir: ./_build/default/_doc/_html