Merge pull request #8199 from kenjis/docs-controller-returns-response

docs: add about Controller returns string/Response

Author: kenjis

user_guide_src/source/incoming/controllers.rst

@@ -11,7 +11,9 @@ Controllers are the heart of your application, as they determine how HTTP reques
 What is a Controller?
 *********************
 
-A Controller is simply a class file that handles a HTTP request. :doc:`URI Routing <routing>` associates a URI with a controller.
+A Controller is simply a class file that handles a HTTP request.
+:doc:`URI Routing <routing>` associates a URI with a controller. It returns a
+view string or ``Response`` object.
 
 Every controller you create should extend ``BaseController`` class.
 This class provides several features that are available to all of your controllers.

user_guide_src/source/installation/upgrade_controllers.rst

@@ -20,6 +20,8 @@ What has been changed
 - CI4 provides :doc:`Request </incoming/incomingrequest>` and :doc:`Responses </outgoing/response>`
   objects for you to work with - more powerful than the CI3-way.
 - If you want a base controller (``MY_Controller`` in CI3), use **app/Controllers/BaseController.php**.
+- Calling ``echo`` within Controllers, as in CI3, is still supported, but
+  it is recommended that a string or Response object be returned from Controllers.
 
 Upgrade Guide
 =============