Ruby update

Gemfile.lock

@@ -205,12 +205,16 @@ GEM
       rb-fsevent (~> 0.10, >= 0.10.3)
       rb-inotify (~> 0.9, >= 0.9.10)
     mercenary (0.3.6)
+    mini_portile2 (2.5.1)
     minima (2.5.1)
       jekyll (>= 3.5, < 5.0)
       jekyll-feed (~> 0.9)
       jekyll-seo-tag (~> 2.1)
     minitest (5.14.4)
     multipart-post (2.1.1)
+    nokogiri (1.11.1)
+      mini_portile2 (~> 2.5.0)
+      racc (~> 1.4)
     nokogiri (1.11.1-x86_64-linux)
       racc (~> 1.4)
     octokit (4.20.0)
@@ -254,6 +258,7 @@ GEM
     zeitwerk (2.4.2)
 
 PLATFORMS
+  ruby
   x86_64-linux
 
 DEPENDENCIES

README.md

@@ -47,7 +47,7 @@ sort: <number>
 Before pushing your edits to the documentation, you may want to see what they
 look like. To do so, you need to:
 
-- have a local [Ruby](https://www.ruby-lang.org) environment
+- have a local [Ruby](https://www.ruby-lang.org) 2.7 environment
 - install the `bundler` and `jekyll` gems
   `gem install bundler jekyll`
 - install this project's specific requirements: