How to update Pi-hole in Docker

Can you (or someone) please explain - step-by-step - how to update Pi-Hole on Docker without loosing any settings og configs.

Thanks @DanSchaper, I have read this guide earlier. It tells me not to do exactly what I want to do ( pihole -up ), but it fails to explain what will happen if I do.
Step 2b tells exactly why I cannot use the preferred method. So even though I understand the preferred method, it is not an option at this point. So my question is really; Will pihole -up screw up my installation and leave me in the dark, or is it likely to work (even if it is not recommended) ?

The guide is detailed and explicit on exactly what to do. pihole -up will not work in docker.