Update OpenCSD/decoder/tests/auto-fdo/autofdo.md to support FSAFDO

[yabinc]

It's recommended by [email protected] in https://lore.kernel.org/lkml/[email protected]/T/#m2f0bbae481bf8984474fcf73fd28988e2bbdd917.

create_llvm_prof prefer to use extbinary format to support FSAFDO, which can provide better
performance improvement:
$ create_llvm_prof --binary= --profile=<perf_file> --format=extbinary --out=<profile_file>

[mikel-armbb]

Thanks for this. I looked at the document and decided that the entire document needs significant updates.
I will include this update in the next patch release.