Visibility culling documentation ?

Ok, so I am back here with new visibility request/question.

On this page one of the bullet points directs me to Precomputed Visibility page, that is actually a page about volumes Volumes Reference | Unreal Engine Documentation, where we have two items at the very bottom of the page, Precomputed Visibility Volume and Precomputed Visibility Override Volume.

There is no explanation, anywhere, how to use them (properly) in the scene (in general and in regards to benefiting performance in Gear VR or mobile in particular) .

Is there any way you could make a mini tutorial about it and then add that to the documentation ?

Thanks.