Add kueue-populator documentation to the Kueue docs page

[j-skiba]

/kind documentation

What would you like to be added:

I would like to see kueue-populator documentation on the official Kueue docs page - https://kueue.sigs.k8s.io/docs

Why is this needed:

Completion requirements:

• there is some reference to kueue-populator documentation on https://kueue.sigs.k8s.io/docs/

This enhancement requires the following artifacts:

The artifacts should be linked in subsequent comments.

[j-skiba]

maybe a separate section here https://kueue.sigs.k8s.io/docs/tasks/manage/ similar to KueueViz

[mimowo]

sgtm