build(deps): bump nokogiri from 1.11.4 to 1.12.5 in /docs

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.11.4 to 1.12.5.
- [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/v1.11.4...v1.12.5

)

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

Signed-off-by: Fabio Utzig <utzig@apache.org>
Signed-off-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Signed-off-by: dependabot[bot] <support@github.com>