Z390 Resizable BAR, DVMT size, and Aperture size BIOS/UEFI setting recommendations

* Guide in question (with link):

Install Guide (Coffee Lake) - https://dortania.github.io/OpenCore-Install-Guide/config.plist/coffee-lake.html#deviceproperties

* Clearly explain the issue:

Trying to install, following the guide, reading everything multiple times and following all recommendations, I would always get to a lines stating:

[ PCI Configuration Begin ]
IOPCIConfigurator::configure kIOPCIEnumerationWaitTime is 900

After a minute or so, it would transition to the prohibited image and stay there. The solution I found was to not only have Resizable BAR enabled and DVMT Pre-Allocate set to 64MB, but also set Aperture Size set to less than 256MB. I believe the lowest this motherboard allows is 128MB (I'll check on next reboot and edit if needed). Only with this value could I make any progress past this stage. I was no able to make it to the installer screen.

* Include possible fixes:

This might be a quirk with Z390 boards (maybe more), but at least for the Coffee Lake guide, perhaps adding a note to set both DVMT Pre-Allocate to 64MB and Aperture Size to less than 256MB in the BIOS would be beneficial. If not there, then perhaps to the troubleshooting section of the guide?