message: Update stable rust in the docs CI builder
diff: @@ -113,6 +113,7 @@ jobs:
  steps:
  - uses: actions/checkout@v2
  - run: rustup update nightly && rustup default nightly
  + - run: rustup update stable
  - run: rustup component add rust-docs
  - run: ci/validate-man.sh
  # This requires rustfmt, use stable.
  