[rubygems/rubygems] Move required_ruby_version gemspec attribute to recommended section.

https://github.com/rubygems/rubygems/commit/de6552ac30

lib/rubygems/specification.rb

@@ -287,6 +287,15 @@ class Gem::Specification < Gem::BasicSpecification
   ######################################################################
   # :section: Recommended gemspec attributes
 
+  ##
+  # The version of Ruby required by this gem
+  #
+  # Usage:
+  #
+  #   spec.required_ruby_version = '>= 2.7.0'
+
+  attr_reader :required_ruby_version
+
   ##
   # A long description of this gem
   #
@@ -522,11 +531,6 @@ class Gem::Specification < Gem::BasicSpecification
     @require_paths = Array(val)
   end
 
-  ##
-  # The version of Ruby required by this gem
-
-  attr_reader :required_ruby_version
-
   ##
   # The RubyGems version required by this gem