add rustdocs to CI and publish to github pages

.github/workflows/build.yaml

@@ -27,4 +27,24 @@ jobs:
     - name: Build
       run: cargo build --verbose --release
     - name: Test
-      run: cargo test --verbose
+      run: cargo test --verbose
+
+  docs:
+    name:  docs
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - id: pages
+        uses: actions/configure-pages@v3
+      - run:  cargo doc --no-deps --all-features
+      - uses: actions/upload-artifact@v2
+        with:
+          path: target/doc
+
+  deploy:
+    environment:
+        url: ${{ steps.deployment.outputs.page_url }}
+    runs-on: ubuntu-latest
+    needs: docs
+    steps:
+      - uses: actions/deploy-pages@v2