util/fipstools: update RSA sigGen cmd args docs

The ACVP.md documentation for the acvptool module wrapper commands
described the "RSA/sigGen/<hash>/pkcs1v1.5" and "RSA/sigGen/<hash>/pss"
commands as only being provided the RSA modulus bit-size, but in
practice the command gets both the bit-size and a message. This commit
updates the docs to match.

Change-Id: I63267bca9855acfb6ba770f3d999fbc6939d283e
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/75127
Reviewed-by: Bob Beck <bbe@google.com>
Reviewed-by: Adam Langley <agl@google.com>
Commit-Queue: Adam Langley <agl@google.com>

util/fipstools/acvp/ACVP.md

@@ -99,8 +99,8 @@ The other commands are as follows. (Note that you only need to implement the com
 | KDF-counter          | Number output bytes, PRF name, counter location string, key (or empty), number of counter bits | key, counter, derived key |
 | KDF-feedback | Number output bytes, PRF name, counter location string, key (or empty), number of counter bits | key, counter, derived key |
 | RSA/keyGen           | Modulus bit-size | e, p, q, n, d |
-| RSA/sigGen/<HASH>/pkcs1v1.5 | Modulus bit-size | n, e, signature |
-| RSA/sigGen/<HASH>/pss       | Modulus bit-size | n, e, signature |
+| RSA/sigGen/<HASH>/pkcs1v1.5 | Modulus bit-size, message | n, e, signature |
+| RSA/sigGen/<HASH>/pss       | Modulus bit-size, message | n, e, signature |
 | RSA/sigVer/<HASH>/pkcs1v1.5 | n, e, message, signature | Single-byte validity flag |
 | RSA/sigVer/<HASH>/pss       | n, e, message, signature | Single-byte validity flag |
 | SHA-1                | Value to hash             | Digest  |