fix: add option update_to_buf_dir in setup

avoid hijacking the tree for use case of users using vim-dirvish

README.md

@@ -47,6 +47,8 @@ require'nvim-tree'.setup {
   auto_close          = false,
   -- opens the tree when changing/opening a new tab if the tree wasn't previously opened
   open_on_tab         = false,
+  -- hijacks new directory buffers when they are opened.
+  update_to_buf_dir   = true,
   -- hijack the cursor in the tree to put it at the start of the filename
   hijack_cursor       = false,
   -- updates the root directory of the tree on `DirChanged` (when your run `:cd` usually)