docs: add ads to leaders cover page

[GangGreenTemperTatum]

PR Checklist 🚨

NA

Proposed changes

NA

Types of changes

NA

• [ ] Bugfix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [x] Documentation Update (if none of the other choices apply)

Checklist

NA

Further comments

CC @virtualsteve-star

[virtualsteve-star]

Please add Scott and John S too

[GangGreenTemperTatum]

Please add Scott and John S too

done - https://github.com/OWASP/www-project-top-10-for-large-language-model-applications/pull/350