Added "Documentation" feature

[mohith10]

Description

The documentation feature helps us provide a URL for documentation of the specific topology deployed on TB. This PR implements that feature. The following modifications have been made:

1. Modified "provider.go": Added a mapping to "resource_documentation.go"

2. Created "resource.documentation.go": Supports CRUD operations of the documentation resource.

3. Modified /examples/provider/provider.tf: Added a documentation resource that assigns the provided URL to the topology.

4. Created /examples/hw_documentation/resource.tf: resource.tf script that creates a topology and assigns the documentation URL.

5. Added docs/resources/documentation.md: Specifying the schema of the documentation resource.

Type of Change

• [ ] Bug Fix
• [x] New Feature
• [ ] Breaking Change
• [ ] Refactor
• [ ] Documentation
• [ ] Other (please describe)

Checklist

• [x] I have read the contributing guidelines
• [x] Existing issues have been referenced (where applicable)
• [x] I have verified this change is not present in other open pull requests
• [x] Functionality is documented
• [x] All code style checks pass
• [x] New code contribution is covered by automated tests
• [x] All new and existing tests pass