[Fix #1203] Insert the target rails version into docs

lib/rubocop/cop/mixin/target_rails_version.rb

@@ -7,6 +7,9 @@ module TargetRailsVersion
       # Informs the base RuboCop gem that it the Rails version is checked via `requires_gem` API,
       # without needing to call this `#support_target_rails_version` method.
       USES_REQUIRES_GEM_API = true
+      # Look for `railties` instead of `rails`, to support apps that only use a subset of `rails`
+      # See https://github.com/rubocop/rubocop/pull/11289
+      TARGET_GEM_NAME = 'railties' # :nodoc:
 
       def minimum_target_rails_version(version)
         if respond_to?(:requires_gem)
@@ -33,11 +36,6 @@ def support_target_rails_version?(version)
           @minimum_target_rails_version <= version
         end
       end
-
-      # Look for `railties` instead of `rails`, to support apps that only use a subset of `rails`
-      # See https://github.com/rubocop/rubocop/pull/11289
-      TARGET_GEM_NAME = 'railties'
-      private_constant :TARGET_GEM_NAME
     end
   end
 end

tasks/cops_documentation.rake

@@ -12,12 +12,19 @@ end
 
 task update_cops_documentation: :yard_for_generate_documentation do
   deps = ['Rails']
+  # NOTE: Insert minimum_target_rails_version after ruby version
+  required_rails_version = lambda do |data|
+    return '' unless (version = data.cop.gem_requirements[RuboCop::Cop::TargetRailsVersion::TARGET_GEM_NAME])
+
+    "NOTE: Required Rails version: #{version.requirements[0][1]}\n\n"
+  end
+  extra_info = { required_ruby_version: required_rails_version }
 
   # NOTE: Update `<<next>>` version for docs/modules/ROOT/pages/cops_rails.adoc
   # when running release tasks.
   RuboCop::Rails::Inject.defaults!
 
-  CopsDocumentationGenerator.new(departments: deps).call
+  CopsDocumentationGenerator.new(departments: deps, extra_info: extra_info).call
 end
 
 desc 'Syntax check for the documentation comments'