Add RouterPi - Compute Module 4 Router Board

[geerlingguy]

I noticed the RouterPi over on Hackaday. It's a simple and tidy CM4 Router Board with dual Ethernet ports:

The first port is provided by the built-in NIC, and the second is through a Realtek RTL8111HS directly off the PCIe bus.

This makes it possible for the build to route at a full 1 Gbps both ways, which some of the USB 3.0-based CM4 router designs can't do. See the full specs on the website, and also see all the project files on ZakKemble's GitHub.

[geerlingguy]

On the site: https://pipci.jeffgeerling.com/boards_cm/routerpi.html