feat: add tokyonight theme

lua/custom/plugins/tokyonight.lua

@@ -0,0 +1,10 @@
+return {
+  'tiagovla/tokyodark.nvim',
+  opts = {
+    -- custom options here
+  },
+  config = function(_, opts)
+    require('tokyodark').setup(opts) -- calling setup is optional
+    vim.cmd [[colorscheme tokyodark]]
+  end,
+}