We usually call the parameter 'digest', but people sometimes think they
can skip the hashing for short inputs are short. I also suspect the term
'digest' is less common. Add warnings about this.
There were also some cases where we called it 'in' and even 'msg'. This
CL fixes those to say 'digest'. Finally, RSA_{sign,verify}_raw are
documented to be building blocks of signature schemes, rather than
signature schemes themselves.
It's unfortunate that EVP_PKEY_sign means "sign a digest", while
EVP_DigestSign means "sign, likely internally digesting it as the first
step", but we're a bit stuck there.
Change-Id: I4c38afff9b6196e2789cf27653fe5e5e8c68c1bf
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/47504
Reviewed-by: Adam Langley <agl@google.com>