Call out TF 0.12+ as requirement
Call out TF 0.12+ as requirement

Change-Id: Idbbdd3e0793f422286d07b591f45ca28c5112e0c

GoogleCloudPlatform/solutions-modern-cicd-anthos,GoogleCloudPlatform/solutions-modern-cicd-anthos,GoogleCloudPlatform/solutions-modern-cicd-anthos