[bot] documentation_updates (#15646)

Co-authored-by: SpacemacsBot <[email protected]>

Author: SpacemacsBot

layers/LAYERS.org

@@ -889,6 +889,7 @@ Features:
 - Support for [[https://github.com/PythonNut/evil-easymotion][=evil-easymotion=]] if the editing style is =vim= or =hybrid=.
 - Support for cycling between multi line block styles via [[https://github.com/IvanMalison/multi-line/][=multi-line=]].
 - Support for editing strings inplace via [[https://github.com/magnars/string-edit.el][=string-edit=]]
+- Presents undo history as a tree via [[https://gitlab.com/tsc25/undo-tree/-/blob/master/undo-tree.el][=undo-tree=]]
 
 ** Spacemacs-editing-visual
 [[file:+spacemacs/spacemacs-editing-visual/README.org][+spacemacs/spacemacs-editing-visual/README.org]]