add personalize mappings and plugins

lua/custom/plugins/harpoon.lua

@@ -0,0 +1,16 @@
+-- You can add your own plugins here or in other files in this directory!
+--  I promise not to create any merge conflicts in this directory :)
+--
+-- See the kickstart.nvim README for more information
+return {
+  'theprimeagen/harpoon',
+  config = function()
+    require('harpoon').setup {}
+
+    local mark = require 'harpoon.mark'
+    local ui = require 'harpoon.ui'
+
+    vim.keymap.set('n', '<leader>a', mark.add_file)
+    vim.keymap.set('n', '<C-e>', ui.toggle_quick_menu)
+  end,
+}