Tweak animation file names to be less confusing in Creating the player scene

It's more verbose, but it's easier to understand and doesn't rely on
the reader knowing how to interpret the `[1/2]` part.

getting_started/first_2d_game/02.player_scene.rst

@@ -69,11 +69,12 @@ Click on the ``SpriteFrames`` you just created to open the "SpriteFrames" panel:
 
 .. image:: img/spriteframes_panel.webp
 
-On the left is a list of animations. Click the "default" one and rename it to
-"walk". Then click the "Add Animation" button to create a second animation named
-"up". Find the player images in the "FileSystem" tab - they're in the ``art``
+On the left is a list of animations. Click the ``default`` one and rename it to
+``walk``. Then click the "Add Animation" button to create a second animation named
+``up``. Find the player images in the FileSystem dock - they're in the ``art``
 folder you unzipped earlier. Drag the two images for each animation, named
-``playerGrey_walk[1/2]`` and ``playerGrey_walk[2/2]``, into the "Animation Frames"
+``playerGrey_walk1``, ``playerGrey_walk2`` (for ``walk``),
+``playerGrey_up1``, and ``playerGrey_up2`` (for ``up``) to the **Animation Frames**
 side of the panel for the corresponding animation:
 
 .. image:: img/spriteframes_panel2.webp