Mention that signals are first-class types since Godot 4.0 in Using signals

(cherry picked from commit d23fe7bd8e)

getting_started/step_by_step/signals.rst

@@ -25,9 +25,17 @@ For example, you might have a life bar on the screen that represents the
 player's health. When the player takes damage or uses a healing potion, you want
 the bar to reflect the change. To do so, in Godot, you would use signals.
 
-.. note:: As mentioned in the introduction, signals are Godot's version of the
-          observer pattern. You can learn more about it here:
-          https://gameprogrammingpatterns.com/observer.html
+Like methods (:ref:`class_callable`), signals are a first-class type since Godot
+4.0. This means you can pass them around as method arguments directly without
+having to pass them as strings, which allows for better autocompletion and is
+less error-prone. See the :ref:`class_signal` class reference for a list of
+what you can do with the Signal type directly.
+
+.. seealso::
+
+    As mentioned in the introduction, signals are Godot's version of the
+    observer pattern. You can learn more about it in
+    `Game Programming Patterns <https://gameprogrammingpatterns.com/observer.html>`__.
 
 We will now use a signal to make our Godot icon from the previous lesson
 (:ref:`doc_scripting_player_input`) move and stop by pressing a button.
@@ -43,8 +51,6 @@ We will now use a signal to make our Godot icon from the previous lesson
             camelCase (See :ref:`doc_c_sharp_styleguide`). Be careful to type
             the method names precisely when connecting signals.
 
-.. Example
-
 Scene setup
 -----------