Bump nokogiri from 1.18.3 to 1.18.4 in /docs

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.18.3 to 1.18.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](https://github.com/sparklemotion/nokogiri/compare/v1.18.3...v1.18.4)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-type: indirect
...

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