Add Lazy setup to README.md

[nimaaskarian]

Added a (hopefully) well configured lazy setup to the README.md

[hasecilu]

A useful key bind.

  keys = {
    {
      "<leader>ct",
      "<cmd>ColorizerToggle<CR>",
      desc = "Toggle color highlighting",
    },
  },

[niderhoff]

to attach this to all buffers by default, you can set event = "BufReadPost", in lazy instead of the filetype options you have in your PR