Fix docs for X509_CRL_get0_by_serial() and X509_CRL_get0_by_cert()

They both return 2 when the revoked entry that's found has the reason
removeFromCRL.

Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/2993)
(cherry picked from commit cdd6c8c5)