Don't generate empty doc sections and reduce code duplication

doc/classes/LightOccluder2D.xml

@@ -9,8 +9,6 @@
 	<tutorials>
 		<link title="2D lights and shadows">https://docs.godotengine.org/en/latest/tutorials/2d/2d_lights_and_shadows.html</link>
 	</tutorials>
-	<methods>
-	</methods>
 	<members>
 		<member name="occluder" type="OccluderPolygon2D" setter="set_occluder_polygon" getter="get_occluder_polygon">
 			The [OccluderPolygon2D] used to compute the shadow.
@@ -21,6 +19,4 @@
 		<member name="sdf_collision" type="bool" setter="set_as_sdf_collision" getter="is_set_as_sdf_collision" default="true">
 		</member>
 	</members>
-	<constants>
-	</constants>
 </class>