add: Create a RELATED.md to list similar projects and SIGs

[shsingh]

Type

Website Issue Report

What would you like to report?

This applies to both the website and documentation content.

• create a page which lists similar:
• OWASP projects
• other committees and SIGs (LF, OpenSSF, CSA)

Code of Conduct

• [X] I agree to follow this project's Code of Conduct

[mik0w]

Hello, I've created a PR: https://github.com/OWASP/www-project-machine-learning-security-top-10/pull/31

[shsingh]

added: RELATED.md as a tab on website #33