Refactor: Missing tests for webhooks and updates for examples

Implementation guide

• Add tests for DeleteProjectHook methods: Currently there are no tests covering the delete functionality. Adding these would improve test coverage and provide usage examples for other developers working with this API.
• Rename test for consistency: The test name TestProjectAddWebhook here should be renamed to TestAddProjectHook to follow naming best practices and maintain consistency with other tests in the codebase.
• Improve webhook example: The webhookExample here could be enhanced by using the existing HookEventType() and HookEventToken() methods instead of parsing headers directly.
• Additional webhook examples: It would be helpful to include examples for creating and deleting webhooks to provide more comprehensive documentation.

If these proposals sounds good enough, I'd be happy to implement these changes myself.