feat: built-in undotree plugin

Author: nathanzeng

init.lua

@@ -129,6 +129,9 @@ do
 
   -- Enable undo/redo changes even after closing and reopening a file
   vim.o.undofile = true
+  -- To open a visual and interactive undo tree, type :Undotree
+  -- See `:help :Undotree`
+  vim.schedule(function() vim.cmd.packadd 'nvim.undotree' end)
 
   -- Case-insensitive searching UNLESS \C or one or more capital letters in the search term
   vim.o.ignorecase = true