grammar: allow do block for (custom) macro

[BlindingDark]

defmodule A do
  use Absinthe.Schema
  
  query do
  end
end

source_file [0, 0] - [7, 0])
  defmodule [0, 0] - [4, 5])
    modulename: alias [0, 10] - [0, 11])
    do_block [0, 12] - [4, 5])
      variable [1, 2] - [1, 5])
      alias [1, 6] - [1, 21])
      variable [3, 2] - [3, 7])
      variable [3, 8] - [3, 10])
  variable [5, 0] - [5, 3])

[Tuxified]

Yup, another good catch. Writing this thing made me realise how flexible Elixirs syntax is :sweat_smile: I'm rephrasing the issue so it reads more like other "TODOs"