Bump nokogiri from 1.19.2 to 1.19.4 in /docs

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.19.2 to 1.19.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/main/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.19.2...v1.19.4)

---
updated-dependencies:
- dependency-name: nokogiri
  dependency-version: 1.19.4
  dependency-type: indirect
...

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

Author: dependabot[bot]

docs/Gemfile.lock

@@ -188,10 +188,10 @@ GEM
     net-smtp (0.5.1)
       net-protocol
     nio4r (2.7.5)
-    nokogiri (1.19.2)
+    nokogiri (1.19.4)
       mini_portile2 (~> 2.8.2)
       racc (~> 1.4)
-    nokogiri (1.19.2-x86_64-linux-gnu)
+    nokogiri (1.19.4-x86_64-linux-gnu)
       racc (~> 1.4)
     parallel (2.1.0)
     parser (3.3.11.1)