Add `delta` explanation to "Dodge the Creeps"

getting_started/step_by_step/your_first_game.rst

@@ -308,9 +308,10 @@ AnimatedSprite animation.
          ``$`` is shorthand for ``get_node()``.
          So in the code above, ``$AnimatedSprite.play()`` is the same as ``get_node("AnimatedSprite").play()``.
 
-Now that we have a movement direction, we can update the player's position
-and use ``clamp()`` to prevent it from leaving the screen by adding the following
-to the bottom of the ``_process`` function:
+Now that we have a movement direction, we can update the player's position. We
+can also use ``clamp()`` to prevent it from leaving the screen. *Clamping* a value
+means restricting it to a given range. Add the following to the bottom of
+the ``_process`` function:
 
 .. tabs::
  .. code-tab:: gdscript GDScript
@@ -328,7 +329,10 @@ to the bottom of the ``_process`` function:
         );
 
 
-.. tip:: *Clamping* a value means restricting it to a given range.
+.. tip:: The `delta` parameter in the `_process()` function refers to the
+        *frame length* - the amount of time that the previous frame took to
+        complete. Using this value ensures that your movement will remain
+        consistent even if the frame rate changes.
 
 Click "Play Scene" (``F6``) and confirm you can move the player
 around the screen in all directions. The console output that opens upon playing
@@ -1149,14 +1153,14 @@ current node at the end of the current frame.
 
     func _on_start_game():
         queue_free()
- 
+
  .. code-tab:: csharp
 
     public void OnStartGame()
     {
         QueueFree();
     }
-          
+
 Then in ``Main.gd`` add a new line inside the ``_on_MobTimer_timeout()`` function,
 at the end.
 
@@ -1166,7 +1170,7 @@ at the end.
     $HUD.connect("start_game", mob, "_on_start_game")
 
  .. code-tab:: csharp
- 
+
     GetNode("HUD").Connect("StartGame", mobInstance, "OnStartGame");
 
 This line tells the new Mob node (referenced by the ``mob`` variable) to respond