Docs/add rubocop minimum version (#2828)

* Add rubocop version in the documentation

* Add reminder to update the documentation when changing the minimum version of Rubocop

* Fix wrong text in the documentation about rubocop being a required dependency

* Replace implicit dependencies text to dependency compatibility

Author: vinibispo

jekyll/index.markdown

@@ -23,6 +23,7 @@ Want to discuss Ruby developer experience? Consider joining the public
     - [With VS Code](#with-vs-code)
     - [With other editors](#with-other-editors)
     - [Composed Ruby LSP bundle](#composed-ruby-lsp-bundle)
+    - [Dependency Compatibility](#dependency-compatibility)
 - [Add-ons](#add-ons)
 - [General features](#general-features)
     - [Hover](#hover)
@@ -88,6 +89,10 @@ project's dependencies).
 The Ruby LSP executable generates a composed bundle with the goal of not requiring users to add the `ruby-lsp` gem to
 their Gemfiles, and at the same time being able to hook into project dependencies. [Learn more](composed-bundle).
 
+### Dependency Compatibility
+
+The Ruby LSP can provide an enhanced experience if RuboCop is present in the project. While using it is optional, if you do choose to include RuboCop, make sure it’s version 1.4.0 or higher.
+
 ## Add-ons
 
 The Ruby LSP provides an add-on system that allows other gems to enhance the base functionality with more editor

lib/ruby_lsp/requests/support/rubocop_runner.rb

@@ -15,6 +15,7 @@
   return
 end
 
+# Remember to update the version in the documentation (usage/dependency-compatibility section) if you change this
 # Ensure that RuboCop is at least version 1.4.0
 begin
   gem("rubocop", ">= 1.4.0")