Bump mermaid from 11.0.2 to 11.2.1 in /docs

Bumps [mermaid](https://github.com/mermaid-js/mermaid) from 11.0.2 to 11.2.1.
- [Release notes](https://github.com/mermaid-js/mermaid/releases)
- [Changelog](https://github.com/mermaid-js/mermaid/blob/develop/CHANGELOG.md)
- [Commits](https://github.com/mermaid-js/mermaid/compare/mermaid@11.0.2...mermaid@11.2.1)

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

Signed-off-by: dependabot[bot] <support@github.com>