install mdbook

.github/workflows/doc.yml

@@ -7,17 +7,28 @@ jobs:
     name: Rust project
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions-rs/toolchain@v1
+      - name: checkout
+        uses: actions/checkout@v2
+
+      - name: rust
+        uses: actions-rs/toolchain@v1
         with:
           toolchain: stable
-      - run: |
-          cargo install mdbook
+
+      - name: mdbook
+        uses: peaceiris/actions-mdbook@v1
+        with:
+          mdbook-version: 'latest'
+
+      - name: build mdbook
+        run: |
           mdbook build docs -d $(pwd)/public
 
-          cargo test
+      - name: build api docs
+        run: |
           cargo doc --workspace --no-deps
           cp -r target/doc public/api
+
       - name: deploy
         uses: JamesIves/github-pages-deploy-action@4.0.0
         with: