[DOCS] complete Tree.get_drop_section_at_position and Tree.drop_mode_flags

doc/classes/Tree.xml

@@ -94,6 +94,8 @@
 			<argument index="0" name="position" type="Vector2">
 			</argument>
 			<description>
+				If [member drop_mode_flags] includes [code]DROP_MODE_INBETWEEN[/code], returns -1 if [code]position[/code] is the upper part of a tree item at that position, 1 for the lower part, and additionally 0 for the middle part if [member drop_mode_flags] includes [code]DROP_MODE_ON_ITEM[/code]. 
+				Otherwise, returns 0. If there are no tree item at [code]position[/code], returns -100.
 			</description>
 		</method>
 		<method name="get_edited" qualifiers="const">
@@ -228,7 +230,7 @@
 			The amount of columns.
 		</member>
 		<member name="drop_mode_flags" type="int" setter="set_drop_mode_flags" getter="get_drop_mode_flags">
-			The drop mode as an OR combination of flags. See [code]DROP_MODE_*[/code] constants.
+			The drop mode as an OR combination of flags. See [code]DROP_MODE_*[/code] constants. Once dropping is done, reverts to [code]DROP_MODE_DISABLED[/code]. Setting this during [method can_drop_data] is recommended.
 		</member>
 		<member name="hide_folding" type="bool" setter="set_hide_folding" getter="is_folding_hidden">
 			If [code]true[/code] the folding arrow is hidden.