Improve own mime type docs for tree dnd

Fixes microsoft#145906

Author: alexr00

src/vscode-dts/vscode.d.ts

@@ -9819,8 +9819,9 @@ declare module 'vscode' {
 		 * The mime types that the {@link TreeDragAndDropController.handleDrop `handleDrop`} method of this `DragAndDropController` supports.
 		 * This could be well-defined, existing, mime types, and also mime types defined by the extension.
 		 *
-		 * Each tree will automatically support drops from its own `DragAndDropController`. To support drops from other trees,
-		 * you will need to add the mime type of that tree. The mime type of a tree is of the format `application/vnd.code.tree.<treeidlowercase>`.
+		 * To support drops from trees, you will need to add the mime type of that tree.
+		 * This includes drops from within the same tree.
+		 * The mime type of a tree is recommended to be of the format `application/vnd.code.tree.<treeidlowercase>`.
 		 *
 		 * To learn the mime type of a dragged item:
 		 * 1. Set up your `DragAndDropController`
@@ -9834,6 +9835,8 @@ declare module 'vscode' {
 		/**
 		 * The mime types that the {@link TreeDragAndDropController.handleDrag `handleDrag`} method of this `TreeDragAndDropController` may add to the tree data transfer.
 		 * This could be well-defined, existing, mime types, and also mime types defined by the extension.
+		 *
+		 * The recommended mime type of the tree will be automatically added.
 		 */
 		readonly dragMimeTypes: string[];
 
@@ -9842,7 +9845,8 @@ declare module 'vscode' {
 		 * Extensions can use `handleDrag` to add their {@link DataTransferItem `DataTransferItem`} items to the drag and drop.
 		 *
 		 * When the items are dropped on **another tree item** in **the same tree**, your `DataTransferItem` objects
-		 * will be preserved. See the documentation for `DataTransferItem` for how best to take advantage of this.
+		 * will be preserved. Use the recommended mime type for the tree (`application/vnd.code.tree.<treeidlowercase>`) to add
+		 * tree objects in a data transfer. See the documentation for `DataTransferItem` for how best to take advantage of this.
 		 *
 		 * To add a data transfer item that can be dragged into the editor, use the application specific mime type "text/uri-list".
 		 * The data for "text/uri-list" should be a string with `toString()`ed Uris separated by newlines. To specify a cursor position in the file,