Fix the treeview deepdive link

docfx/articles/index.md

@@ -3,4 +3,4 @@
 * [Terminal.Gui Overview](overview.html)
 * [Keyboard Event Processing](keyboard.html)
 * [Event Processing and the Application Main Loop](mainloop.md)
-* [TreeView Deep Dive](articles/treeview.md)
+* [TreeView Deep Dive](treeview.md)