[Security] Bump rexml from 3.2.4 to 3.2.5 in /docs (#3714)

Bumps [rexml](https://github.com/ruby/rexml) from 3.2.4 to 3.2.5. **This update includes a security fix.**
- [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-preview[bot] <support@dependabot.com>

Co-authored-by: dependabot-preview[bot] <27856297+dependabot-preview[bot]@users.noreply.github.com>

docs/Gemfile.lock

@@ -225,7 +225,7 @@ GEM
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rexml (3.2.4)
+    rexml (3.2.5)
     rouge (3.26.0)
     ruby-enum (0.9.0)
       i18n