npm: bump markdownlint-cli from 0.39.0 to 0.40.0

Bumps [markdownlint-cli](https://github.com/igorshubovych/markdownlint-cli) from 0.39.0 to 0.40.0.
- [Release notes](https://github.com/igorshubovych/markdownlint-cli/releases)
- [Commits](igorshubovych/markdownlint-cli@v0.39.0...v0.40.0)

---
updated-dependencies:
- dependency-name: markdownlint-cli
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <[email protected]>