Add OS/2 build instructions since our binaries don't work.
Add OS/2 build instructions since our binaries don't work.

Distrotech/nasm,letolabs/nasm,projedi/nasm,projedi/nasm,Distrotech/nasm,projedi/nasm,techkey/nasm,turingstudio/nasm,turingstudio/nasm,turingstudio/nasm,Distrotech/nasm,techkey/nasm,techkey/nasm,projedi/nasm,techkey/nasm,projedi/nasm,techkey/nasm,turingstudio/nasm,Distrotech/nasm,letolabs/nasm,letolabs/nasm