Bump nokogiri from 1.13.3 to 1.13.4 in /docs

Bumps [nokogiri](https://github.com/sparklemotion/nokogiri) from 1.13.3 to 1.13.4.
- [Release notes](https://github.com/sparklemotion/nokogiri/releases)
- [Changelog](https://github.com/sparklemotion/nokogiri/blob/v1.13.4/CHANGELOG.md)
- [Commits](sparklemotion/nokogiri@v1.13.3...v1.13.4)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

docs/Gemfile.lock

@@ -234,9 +234,11 @@ GEM
       jekyll-seo-tag (~> 2.1)
     minitest (5.15.0)
     multipart-post (2.1.1)
-    nokogiri (1.13.3)
+    nokogiri (1.13.4)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
+    nokogiri (1.13.4-x64-mingw32)
+      racc (~> 1.4)
     octokit (4.22.0)
       faraday (>= 0.9)
       sawyer (~> 0.8.0, >= 0.5.3)
@@ -274,6 +276,7 @@ GEM
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.8)
+    unf_ext (0.0.8-x64-mingw32)
     unicode-display_width (1.8.0)
     wdm (0.1.1)
     webrick (1.7.0)