Possibility to split the large collection of hex files into a sperate repo

[mcuee]

• Better documentation for compiling optiboot Optiboot/optiboot#355 (comment)

Right now the big hex file collections are convenient for users but a bit problematic if you change something and build, then git diff will be huge.

[mcuee]

@MCUdude

But this is probably personal taste and I think you have good reasons to organize in this way. Therefore I will close this issue.