[main] Updating Docs in file modules/ROOT/pages/provisioning-raspberry-pi4.adoc

[wahahawasabi]

Regarding Installing FCOS and Booting via U-Boot, should the docs for this quote be updated (thereby updating the coreos-installer command as well:

We pass in --append-karg nomodeset here to workaround an issue where monitor output will be lost during system boot.

Because it seems like the issue was closed in June 2024.