Add note about Terraform State

[aknot242]

Is your feature request related to a problem? Please describe

The solution makes use of local TF state file(s) by default.

Describe the solution you'd like

While it shouldn't be expected that this repo would provide alternate options for storing state, perhaps a note in the readme as to how/where TF state is kept, and perhaps a link to instructions regarding how the user could adapt this solution to use Terraform Cloud. Thanks for your consideration.