Update area_create description in PhysicsServer2D/3D to clear up possible confusions

doc/classes/PhysicsServer2D.xml

@@ -52,7 +52,8 @@
 		<method name="area_create">
 			<return type="RID" />
 			<description>
-				Creates a 2D area object in the physics server, and returns the [RID] that identifies it. Use [method area_add_shape] to add shapes to it, use [method area_set_transform] to set its transform, and use [method area_set_space] to add the area to a space.
+				Creates a 2D area object in the physics server, and returns the [RID] that identifies it. The default settings for the created area include a collision layer and mask set to [code]1[/code], and [code]monitorable[/code] set to [code]false[/code].
+				Use [method area_add_shape] to add shapes to it, use [method area_set_transform] to set its transform, and use [method area_set_space] to add the area to a space. If you want the area to be detectable use [method area_set_monitorable].
 			</description>
 		</method>
 		<method name="area_get_canvas_instance_id" qualifiers="const">

doc/classes/PhysicsServer3D.xml

@@ -44,7 +44,8 @@
 		<method name="area_create">
 			<return type="RID" />
 			<description>
-				Creates an [Area3D].
+				Creates a 3D area object in the physics server, and returns the [RID] that identifies it. The default settings for the created area include a collision layer and mask set to [code]1[/code], and [code]monitorable[/code] set to [code]false[/code].
+				Use [method area_add_shape] to add shapes to it, use [method area_set_transform] to set its transform, and use [method area_set_space] to add the area to a space. If you want the area to be detectable use [method area_set_monitorable].
 			</description>
 		</method>
 		<method name="area_get_collision_layer" qualifiers="const">