[BUG]: Documentation improvement - GPT on rPi 4B (fix for black screen/no HDMI out, 4x green LED on boot)

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Current Behavior

GPT is supported on rPi 4B, BUT- and I found this out after an embarrassing amount of hours- older EEPROM firware will NOT work. You just get the 4x green (ACT) LED sequence (indicating boot media not found) and a black/no display (no HDMI out).

The AlmaLinux 9 MBR image worked fine, the 9 GPT image exhibited the above behavior, the 10 image (GPT only) exhibited the above behavior.

I got two rPi 4Bs shortly after launch and had never run Raspbian on them (always used Arch Linux ARM), and thus any forced EEPROM firmware updates they may have pushed out I never got. (The firmware was so old that I never even got the bootloader menu/messages/menu/display, etc.)

It may be worth mentioning that if this occurs, one should create a bootable medium with [`rpi-imager`](https://www.raspberrypi.com/software/)[0] and boot the Bootloader image (__Misc utility images > Bootloader (Pi 4 family)__) to update the EEPROM firmware (it'll sit at a green screen when done).

The ALmaLinux 10 image (GPT only offered) worked fine for me after that.

[0] There's probably a way to download the image directly but couldn't be arsed to intercept the HTTPS stream to get the URL at the moment.

### Expected Behavior

N/A

### Steps To Reproduce

N/A

### Anything else?

N/A

### Search terms

green led 4 black blank screen 4b gpt mbr