README.md: update neo-tree example - remove legacy setting (#744)

Author: dam9000

README.md

@@ -140,9 +140,6 @@ This will install the tree plugin and add the command `:Neotree` for you. For mo
 In the file: `lua/custom/plugins/filetree.lua`, add:
 
 ```lua
--- Unless you are still migrating, remove the deprecated commands from v1.x
-vim.cmd([[ let g:neo_tree_remove_legacy_commands = 1 ]])
-
 return {
   "nvim-neo-tree/neo-tree.nvim",
   version = "*",