Feat: Improved Structure

[amaanx86]

This pull request introduces significant improvements to the GitLab Groups Terraform module by updating documentation, usage examples, and configuration structure. The core changes are focused on standardizing module usage with the official Terraform Registry source, enhancing documentation for contributors and users, and providing more comprehensive and security-focused example configurations.

Documentation and Contribution Process Improvements:

• Added a detailed contributing guide at .github/contributing.md with step-by-step instructions, semantic commit guidelines, and testing requirements for contributors.
• Updated the README.md to reference the new contributing guide, replacing the previous contribution instructions with a link for clarity and maintainability.

Module Usage and Example Updates:

• Refactored all example module usages in README.md and examples/main.tf to use the official Terraform Registry source (sudo-terraform-modules/groups/gitlab) and specify the version (0.2.0), ensuring consistency and easier upgrades. [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
• Added a comprehensive examples/README.md describing the organizational structure, security features, and usage of the example Terraform configurations, making it easier for users to understand and adopt best practices.
• Enhanced the README.md with a new section pointing to the expanded examples directory, including details about enterprise setups and specialized configurations.

Security and Licensing Updates:

• Changed the module license from MIT to Apache 2.0 in README.md, reflecting a more standard open-source license for Terraform modules.

Module Structure and Maintainer Information:

• Improved documentation of the module structure and added maintainer information to README.md for transparency and support. [1] [2]

These changes collectively make the module easier to use, contribute to, and integrate into enterprise environments, while also improving security, maintainability, and documentation clarity.