terraform-docs to show input variables in README

[nitrocode]

Hi @dumrauf. This is a very cool module. Thank you for creating and maintaining it.

I noticed that the README does not include the inputs to the module and I've found this to be pretty helpful in all the cloudposse modules (e.g. cloudposse/terraform-aws-ecs-alb-service-task)

Have you considered using terraform-docs ? would you be open to a pull request ?