Update plan-template and README for improved clarity and structure

- Changed reference in plan-template from constitution document to main README for Constitution Check section.
- Revised README to streamline the introduction, emphasizing the workflow's benefits and phases.
- Consolidated and clarified the workflow orchestration and job descriptions for better understanding.
- Updated configuration examples and added details on setup and teardown scripts for testing.
- Enhanced the organization of sections for easier navigation and comprehension.

Author: MariusStorhaug