[Content suggestion] Add warning about safety of using kernel manager after update

Hello, I tinkered with kernel manager and noticed behaviour that if you updated system and it recommended you to perform reboot then it's really matter to reboot and only then change kernel. So snapshots helped a lot and it was really easy. But being kernel-less and unable to install at least previous one which you just deleted few seconds ago or install new one is not quite good. So maybe something like that would be nice to see in wiki. In my case it failed to perform `mkinitramfs` but I'm not sure why. After restore, update and reboot everything worked including kernel manager and kernel changing.

As addition I would like to add screenshot of "Reboot recommended" notification in KDE Plasma which CachyUpdate sends you in case of reboot needed after performing update.

Breeze:

Papirus:

Start by locating the wiki page or section covering kernel manager and the “Reboot recommended” notification. Review the reported update, reboot, kernel-change sequence and the mkinitramfs failure context; done means the wiki includes a clear warning, with the provided notification screenshots if appropriate.

Written by the indexing model from the issue text.