Add Raspberry Pi 5 to the support list

Author: fhunleth

README.md

@@ -48,6 +48,7 @@ by the boards they support:
 * `rpi3` - Raspberry Pi 3 Model B and Model B+
 * `rpi3a` - Raspberry Pi 3 Model A+ and Raspberry Pi Zero 2 W
 * `rpi4` - Raspberry Pi 4 Model B
+* `rpi5` - Raspberry Pi 5
 * `osd32mp1` - Octavo OSD32MP1-BRK
 * `npi_imx6ull` - Seeed Studio imx6ull (select the MicroSD boot mode switches)
 * `mangopi_mq_pro` - An Allwinner D1 (RISC-V) board