Enhance readme with API access and FAQ sections

[jeffpaul]

Description of the Change

This pull request updates the readme.md documentation for the WP-CLI Vulnerability Scanner plugin. The main changes clarify API options and add a new FAQ section for security reporting.

Documentation improvements:

• Clarified that users can choose between WPScan, Patchstack, and Wordfence Intelligence APIs, and explained how to configure the API service in wp-config.php.
• Improved section formatting for the global command instructions.

Security and support information:

• Added a new "Frequently Asked Questions" section, including instructions on how to report security bugs via the Patchstack Vulnerability Disclosure Program.

How to test the Change

Changelog Entry

Developer - Add Patchstack security-reporting FAQ.

Credits

Props @jeffpaul.

Checklist:

• I agree to follow this project's Code of Conduct.
• I have updated the documentation accordingly.
• I have added Critical Flows, Test Cases, and/or End-to-End Tests to cover my change.
• All new and existing tests pass.