Terraform Cloud and Branch Planner integration docs

[chanwit]

User Story

As a DevOps engineer,
I'd like to have clear and concise documentation on integrating Terraform Cloud with the Branch Planner,
so that I can seamlessly manage my infrastructure across branches and environments using Terraform.

Acceptance Criteria

• The documentation should provide a step-by-step guide for integrating Terraform Cloud with the Branch Planner component.
• The documentation should include any prerequisite setup, configuration, or dependencies required for the integration.
• The documentation should be added to the official Terraform Controller documentation.