doc: Make docs.godotengine.org links point to 3.2 branch

doc/classes/AnimationNodeAdd2.xml

@@ -7,7 +7,7 @@
 		A resource to add to an [AnimationNodeBlendTree]. Blends two animations additively based on an amount value in the [code][0.0, 1.0][/code] range.
 	</description>
 	<tutorials>
-		<link>https://docs.godotengine.org/en/latest/tutorials/animation/animation_tree.html</link>
+		<link>https://docs.godotengine.org/en/3.2/tutorials/animation/animation_tree.html</link>
 	</tutorials>
 	<methods>
 	</methods>