ci: check rustdocs on build

Author: jlizen

.github/actions/rust-build/action.yml

@@ -29,3 +29,9 @@ runs:
       if: ${{ inputs.run-tests == 'true' }}
       shell: bash
       run: cargo test --all-features --verbose --package ${{ inputs.package }}
+
+    - name: Check documentation
+      env:
+          RUSTFLAGS: --cfg docsrs 
+          RUSTDOCFLAGS: --cfg docsrs -Dwarnings
+      run: cargo doc --no-deps --document-private-items --all-features