Bump nokogiri from 1.18.9 to 1.19.1 in /docs

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.18.9 to 1.19.1.
- [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/v1.18.9...v1.19.1)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-version: 1.19.1
  dependency-type: indirect
...

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