remove warning in upgradescript 7.2 to 7.2

[baumhof]

When upgrading from 7.2 to 7.3 there is a stark warning which has to be typed in: I have been warned!
Now that 7.3 is not Beta anymore, we might step down a little by just displaying a Remark on freshly made Backups or something like that.

Yours
Holger