ci: build documentation and forbid warnings

.github/workflows/ci.yml

@@ -229,3 +229,20 @@ jobs:
 
       - name: Verify release artifact
         run: ./ci/verify_android_release.sh
+
+  docs:
+    name: Check for documentation errors
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout sources
+        uses: actions/checkout@v3
+        with:
+          persist-credentials: false
+
+      - name: Install rust toolchain
+        uses: dtolnay/rust-toolchain@nightly
+
+      - name: Build documentation
+        run: cargo doc --locked --all-features --no-deps --document-private-items
+        env:
+          RUSTDOCFLAGS: -Dwarnings