Update instructions for neo-tree set up (nvim-lua#200)

For me, setting this variable in the config function didn't work. Putting it outside the return block did the trick.

README.md

@@ -64,6 +64,9 @@ This will automatically install `nvim-autopairs` and enable it on startup. For m
 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 = "*",
@@ -73,9 +76,6 @@ return {
     "MunifTanjim/nui.nvim",
   },
   config = function ()
-    -- Unless you are still migrating, remove the deprecated commands from v1.x
-    vim.cmd([[ let g:neo_tree_remove_legacy_commands = 1 ]])
-
     require('neo-tree').setup {}
   end,
 }