Add example of a definition of a Set field in a Collection field to Set/Collection Docs

There is an example how to define and print Set field in a collection here https://docs.boltcms.io/5.0/howto/transform-repeaters-to-sets-and-collections#repeater-collection-with-1-set.

I think it would be helpful to add that example on the [Collection](https://docs.boltcms.io/5.0/fields/collection#jumpbutton) and [Set](https://docs.boltcms.io/5.0/fields/set) fields docs as well?