Replace cidr_block with ipv4_cidr_block in README

[Majin Buu (MajinBuuOnSecurity)]

Solves #121, see https://github.com/cloudposse/terraform-aws-dynamic-subnets#usage for further evidence.

[Joe Niland (joe-niland)]

Hi Majin Buu (@MajinBuuOnSecurity)

Thanks for your PR.
To make this change, please update README.yaml then run:

make init
make readme

[Hans Donner (hans-d)]

/terratest

[Hans Donner (hans-d)]

From the top of the READme file involved

  ** DO NOT EDIT THIS FILE
  **
  ** This file was automatically generated by the `cloudposse/build-harness`.
  ** 1) Make all changes to `README.yaml`
  ** 2) Run `make init` (you only need to do this once)
  ** 3) Run`make readme` to rebuild this file.

Majin Buu (@MajinBuuOnSecurity) Can you apply the fix to the right file and execute the rebuild?

[mergify]

Thanks Majin Buu (@MajinBuuOnSecurity) for creating this pull request!

A maintainer will review your changes shortly. Please don't be discouraged if it takes a while.

While you wait, make sure to review our contributor guidelines.

Tip

Need help or want to ask for a PR review to be expedited?

Join us on Slack in the #pr-reviews channel.