Changes

docs(README): Revise and expand CI/CD documentation for clarity and structure (#3437)

- Updated the introduction to provide a comprehensive overview of the
repository's purpose.
- Enhanced the organization of CI pipeline components and repository
structure with detailed descriptions and diagrams.
- Added sections on modifying and testing pipelines, including a
step-by-step guide and workflow diagram.
- Clarified the file structure and naming conventions for Prow jobs,
Jenkins jobs, and pipelines.
- Included links to relevant directories for easier navigation.
 (commit: d43a1e0)