[FEATURE] Update Terraform section to reflect v0.13

[noinarisak]

Is your feature request related to a problem? Please describe. Update the documentation to mention that the HCL script in /terraform director only support v0.12.x.

Describe the solution you'd like Update the documentation to be more explicit

Describe alternatives you've considered Update each HCL scripts with the following:

$ terraform 0.13upgrade .

$ terraform init

Additional context n/a