Check for doc failures in CI

Author: cowlicks

.github/workflows/ci.yml

@@ -7,6 +7,7 @@ on:
 env:
   CARGO_TERM_COLOR: always
   RUSTFLAGS: "-Dwarnings"
+  RUSTDOCFLAGS: "-Dwarnings"
 
 jobs:
   build_and_test:
@@ -24,4 +25,5 @@ jobs:
       - run: rustup update ${{ matrix.toolchain }} && rustup default ${{ matrix.toolchain }}
       - run: cargo build --verbose
       - run: cargo test --verbose
+      - run: cargo doc
       - run: rustup component add clippy && cargo clippy --all-targets