Add explanation about PS_VERSION_DB mismatch

[Quetzacoalt91]

Questions	Answers
Branch?	8.x
Description?	A check is added to the upgrade module about the PS_VERSION_DB, where we require merchants to have an up to date database before starting another upgrade on top of it. Not doing so leads to duplicate SQL requests to be executed, or some of them missing.
Fixed ticket?	Partially fixes https://github.com/PrestaShop/PrestaShop/issues/33856 with https://github.com/PrestaShop/autoupgrade/pull/696