Fix presumed copy/paste error: "Returns" -> "Sets"

I might be going out on a limb here... :D

(cherry picked from commit e38b63400cc6f3c7d83c7414c928d85bc82dab59)

doc/classes/Skeleton.xml

@@ -230,7 +230,7 @@
 			<argument index="1" name="pose" type="Transform">
 			</argument>
 			<description>
-				Returns the pose transform for bone [code]bone_idx[/code].
+				Sets the pose transform for bone [code]bone_idx[/code].
 			</description>
 		</method>
 		<method name="set_bone_rest">