[DOCS] Add tutorial link to Particles2D

(cherry picked from commit bc8aa32593)

doc/classes/Particles2D.xml

@@ -8,6 +8,7 @@
 		Use the [code]process_material[/code] property to add a [ParticlesMaterial] to configure particle appearance and behavior. Alternatively, you can add a [ShaderMaterial] which will be applied to all particles.
 	</description>
 	<tutorials>
+		<link>https://docs.godotengine.org/en/latest/tutorials/2d/particle_systems_2d.html</link>
 	</tutorials>
 	<demos>
 	</demos>