add new CI step for documentation checking (#51)

Author: makspll

.github/workflows/ci.yml

@@ -81,4 +81,23 @@ jobs:
       - uses: actions-rs/cargo@v1
         with:
           command: test
-          args: --workspace --features=lua54,rhai,teal,lua_script_api,rhai_script_api
+          args: --workspace --features=lua54,rhai,teal,lua_script_api,rhai_script_api
+  docs:
+    name: Docs
+    runs-on: ubuntu-latest
+    steps:
+      - name: Install alsa and udev
+        run: sudo apt-get update; sudo apt-get install --no-install-recommends libasound2-dev libudev-dev
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          toolchain: stable
+          override: true
+      - uses: Swatinem/rust-cache@v2.2.0
+      - name: Find docs.rs features
+        run: echo "DOCS_FEATURES=$(cargo metadata --no-deps | python -c "import sys,json; [print(','.join(x['metadata']['docs.rs']['features'])) for x in json.load(sys.stdin)['packages'] if x['name'] == 'bevy_mod_scripting']")" >> $GITHUB_OUTPUT
+        id: features
+      - uses: actions-rs/cargo@v1
+        with:
+          command: doc
+          args: --workspace --features=${{ steps.features.outputs.DOCS_FEATURES }}