Help improving the installation guide and support hardware lists

[nia <nia%NetBSD.org@localhost>]

These files are contain lots of outdated information:

- src/distrib/notes/evbarm/hardware
- src/distrib/notes/evbarm/install

I'd like to bring these up to date, hopefully in time for 9.1.

In particular, instructions for the following are missing and
would be useful:

- Installing a NetBSD on RPI using standard images
- Installing to a HDD using sysinst
- Installing on SBSA/ACPI hardware
- Preparing images from Windows (without dd?)
- installboot U-Boot stuff...?

They list support for the following old hardware:

- Technologic Systems TS-7200
- ARM, Ltd. Integrator
- Intel IQ80310
- Intel IQ80321
- Team ASA, Inc. Npwr
- Intel IXM1200
- Samsung SMDK2800
- ADI Engineering, Inc. BRH ("Big Red Head")
- Arcom Viper 

I'm curious if anyone still has these and can test them.
Otherwise, the information is misleading at best and should
probably be removed.