Bump nokogiri from 1.11.5 to 1.12.5 in /docs (#399)

Author: dependabot[bot]

docs/Gemfile.lock

@@ -211,15 +211,15 @@ GEM
       rb-inotify (~> 0.9, >= 0.9.7)
       ruby_dep (~> 1.2)
     mercenary (0.3.6)
-    mini_portile2 (2.5.1)
+    mini_portile2 (2.6.1)
     minima (2.4.1)
       jekyll (~> 3.5)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     minitest (5.11.3)
     multipart-post (2.1.1)
-    nokogiri (1.11.5)
-      mini_portile2 (~> 2.5.0)
+    nokogiri (1.12.5)
+      mini_portile2 (~> 2.6.1)
       racc (~> 1.4)
     octokit (4.14.0)
       sawyer (~> 0.8.0, >= 0.5.3)