build(deps): bump rexml from 3.2.4 to 3.2.5 in /docs

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.4 to 3.2.5.
- [Release notes](https://github.com/ruby/rexml/releases)
- [Changelog](https://github.com/ruby/rexml/blob/master/NEWS.md)
- [Commits](https://github.com/ruby/rexml/compare/v3.2.4...v3.2.5

)

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