[coreboot] Official builds for EoL Chromebooks

[Emilian Bold]

Hello,

Now that Coreboot has reproducible builds, could you provide a list of
build hashes for Chromebooks that are or will soon reach End of Life?

I see on https://support.google.com/chrome/a/answer/6220366?hl=en that 2
Chromebooks will reach End of Life in 2016 and 3 more in 2017 then 7 in
2018. I assume the number will increase each year.

I know that Coreboot does not distribute builds, but the little Custom roms
section on https://www.coreboot.org/users.html seems insufficient.

It's easy making a build, you just need to have the certainty you did it
well. Or that the one you are downloading is correct.

Posting an official SHA-256 hash for a ROM would solve this.

--emi