Massive change in OLD docker-compose.yml vs NEW compose.yaml structure - migration method undocumented

I am about to upgrade from 11.4 to 11.5 and the upgrade is "plug and pray" in the sense that it is not documented exactly how to go about it. So much change, with new override file, new secrets structure, and none of this documented as far as I can tell. What is the proper method to upgrade safely please, anyone done it, step by step. Thanks!