Bump nokogiri from 1.15.4 to 1.18.4 in /docs

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.15.4 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/v1.15.4...v1.18.4)

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

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

docs/Gemfile.lock

@@ -210,7 +210,9 @@ GEM
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     minitest (5.19.0)
-    nokogiri (1.15.4-aarch64-linux)
+    nokogiri (1.18.4-aarch64-linux-gnu)
+      racc (~> 1.4)
+    nokogiri (1.18.4-x86_64-linux-gnu)
       racc (~> 1.4)
     octokit (4.25.1)
       faraday (>= 1, < 3)
@@ -218,7 +220,7 @@ GEM
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
     public_suffix (4.0.7)
-    racc (1.7.1)
+    racc (1.8.1)
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
@@ -250,6 +252,7 @@ GEM
 
 PLATFORMS
   aarch64-linux
+  x86_64-linux
 
 DEPENDENCIES
   github-pages