added nvim-tree and setup keymap to toggle file-browser

lua/custom/plugins/nvim-tree.lua

@@ -0,0 +1,39 @@
+-- NVIM tree
+-- a file explore plugin
+
+local function on_nvim_tree_attach(bufnr)
+	local api = require("nvim-tree.api")
+
+	local function opts(desc)
+		return { desc = "nvim-tree: " .. desc, buffer = bufnr, noremap = true, silent = true, nowait = true }
+	end
+
+	-- default mappings
+	api.config.mappings.default_on_attach(bufnr)
+
+	-- custom mappings
+	-- vim.keymap.set('n', '<C-t>', api.tree.change_root_to_parent,        opts('Up'))
+	-- vim.keymap.set('n', '?',     api.tree.toggle_help,                  opts('Help'))
+	vim.keymap.set('n', '<C-b>', api.tree.toggle, opts('Toggle tree'))
+end
+
+return {
+	"nvim-tree/nvim-tree.lua",
+	version = "*",
+	--
+	-- after = "nvim-web-devicons",
+	-- requires = "nvim-tree/nvim-web-devicons",
+	dependencies = {
+		"nvim-tree/nvim-web-devicons",
+	},
+	config = function()
+		require("nvim-tree").setup {
+			update_cwd = true,
+			update_focused_file = {
+				enable = true
+			},
+			respect_buf_cwd = true,
+			on_attach = on_nvim_tree_attach,
+		}
+	end,
+}