feat: added nerdtree extension

lua/lualine/extensions/nerdtree.lua

@@ -0,0 +1,16 @@
+-- Copyright (c) 2020-2021 hoob3rt
+-- MIT license, see LICENSE for more details.
+
+local M = {}
+
+M.sections = {
+  lualine_a = { vim.fn.getcwd },
+}
+
+M.inactive_sections = {
+  lualine_a = { vim.fn.getcwd },
+}
+
+M.filetypes = { 'nerdtree' }
+
+return M