Wrong command syntax '--sort-by-required'

I'm a first-time user, but it seems to me that
`--sort-by-required` should be `--sort-by required`
It is wrong in several places in the readme.

https://github.com/cytopia/docker-terraform-docs/blob/master/README.md

I ran the command below to figure out the proper syntax
`docker run --rm -v $(pwd):/data cytopia/terraform-docs terraform-docs help`