Update Particles2D instructions to convert GPU to CPU (godotengine#8525)

* Update Particles2D instructions to convert GPU to CPU

Author: judebert

tutorials/2d/img/particles_convert.png

@@ -33,10 +33,10 @@ While GPUParticles2D is configured via a :ref:`class_ParticleProcessMaterial`
 node properties in CPUParticles2D (with the exception of the trail settings).
 
 You can convert a GPUParticles2D node into a CPUParticles2D node by clicking on
-the node in the inspector, and selecting **Particles > Convert to
-CPUParticles2D** in the toolbar at the top of the 3D editor viewport.
+the node in the inspector, selecting the 2D viewport, and selecting
+**GPUParticles2D > Convert to CPUParticles2D** in the viewport toolbar.
 
-.. image:: img/particles_convert.png
+.. image:: img/particles_convert.webp
 
 The rest of this tutorial is going to use the GPUParticles2D node. First, add a GPUParticles2D
 node to your scene. After creating that node you will notice that only a white dot was created,