try linking info about cache types

[matkoniecz]

(though one potential trap is that example at tagged commit will still link latest docs - is there a better way to do this?)

Maybe it should mention docs in general or just mention that there are different cache modes?

[lonvia]

This would be normally fine. I just happen to be in the middle of a complete overhaul of the documentation, so don't want to add links at this point which will be invalid very soon.

Thank you nonetheless.