No example for custom UI

[Mardoxx]

Check that this is really a bug

• [X] I confirm

Reproduction link

https://swiperjs.com/demos

Bug description

Custom UI elements example missing

Expected Behavior

No response

Actual Behavior

No response

Swiper version

Platform/Target and Browser Versions

Validations

• [X] Follow our Code of Conduct
• [X] Read the docs.
• [X] Check that there isn't already an issue that request the same feature to avoid creating a duplicate.
• [X] Make sure this is a Swiper issue and not a framework-specific issue

Would you like to open a PR for this bug?

• [ ] I'm willing to open a PR