update and enable my todo comment highlighter

lua/core/init.lua

@@ -31,6 +31,7 @@ local M = {
   misc = require("core.misc"),
   lsp = require("core.lsp"),
   color = require("core.color"),
+  todo = require("core.todo"),
   snippets = vim.fs.joinpath(vim.fn.stdpath("config"), "lua/core/snippets.lua"),
 }