fixup! Add a note about calling super

Author: pirj

docs/modules/ROOT/pages/upgrade_to_version_2.adoc

@@ -9,6 +9,7 @@ In version 2.x:
  - `CustomIncludeMethods` configuration option for `RSpec/EmptyExampleGroup` is removed
  - cop departments are nested for cops with a department that doesn’t match the extension name (`Capybara`, `FactoryBot`, `Rails`)
  - `AllCops/RSpec/Patterns`/`AllCops/FactoryBot/Patterns` options are removed
+ - Calling `super` from `on_new_investigation` defined in a cop is mandatory now
 
 [discrete]
 === Adjust the configuration of `RSpec/EmptyExampleGroup`
@@ -216,6 +217,30 @@ Examples#regular
 
 https://github.com/rubocop-hq/rubocop-rspec/pull/956[Pull request with more examples].
 
+=== Always call `super` from `on_new_investigation` in your cops
+
+`on_new_investigation` is now used for internal purposes, and not calling `super` from your cop involves a risk of configuration not being properly loaded, and dynamic RSpec DSL matchers won't work.
+
+NOTE: You don't have to define `on_new_investigation` in your cops unless you need to.
+
+[source,ruby]
+----
+module RuboCop
+  module Cop
+    module RSpec
+      class MultipleMemoizedHelpers < Base
+        def on_new_investigation
+          super # Always call `super`
+          @example_group_memoized_helpers = {}
+        end
+      end
+    end
+  end
+end
+----
+
+https://github.com/rubocop-hq/rubocop-rspec/pull/956[Pull request with more examples].
+
 === Conform with RuboCop API Changes
 
 The parent project, RuboCop, has API changes.