add nvim configs

.config/nvim/lua/plugins/undotree.lua

@@ -0,0 +1,8 @@
+return {
+  "jiaoshijie/undotree",
+  dependencies = "nvim-lua/plenary.nvim",
+  config = true,
+  keys = { -- load the plugin only when using it's keybinding:
+    { "<leader>u", "<cmd>lua require('undotree').toggle()<cr>" },
+  },
+}