Update README.md

Author: holiber

README.md

@@ -150,7 +150,7 @@ interface ICursorPosition<TDataType> {
 | toggle     | ISlTreeNode | Slot for expand/collapse button                                                               |
 | sidebar    | ISlTreeNode | Sidebar content                                                                               |
 | draginfo   | SlVueTree   | Slot that follows the mouse cursor while dragging. By default shows the dragging nodes count. |
-| node-empty | ISlTreeNode | Slot for (optional) message when folder is open, but empty                                    |
+| empty-node | ISlTreeNode | Slot for (optional) message when folder is open, but empty                                    |
 
 
 ## Example: