Bump nokogiri from 1.18.4 to 1.18.9 in /docs

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-version: 1.18.9
  dependency-type: indirect
...

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

Author: dependabot[bot]

docs/Gemfile.lock

@@ -91,9 +91,9 @@ GEM
       jekyll-seo-tag (~> 2.1)
     minitest (5.24.1)
     mutex_m (0.2.0)
-    nokogiri (1.18.4-arm64-darwin)
+    nokogiri (1.18.9-arm64-darwin)
       racc (~> 1.4)
-    nokogiri (1.18.4-x86_64-linux-gnu)
+    nokogiri (1.18.9-x86_64-linux-gnu)
       racc (~> 1.4)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)