[openssl/openssl] 9cef2a: Update SIV mode documentation

[pauli]

  Branch: refs/heads/master
  Home:   https://github.openssl.org/openssl/openssl
  Commit: 9cef2a70b151b6a92eb1770ceb5fa90331305934
      https://github.openssl.org/openssl/openssl/commit/9cef2a70b151b6a92eb1770ceb5fa90331305934
  Author: Todd Short <tshort at akamai.com>
  Date:   2022-06-09 (Thu, 09 Jun 2022)

  Changed paths:
    M doc/man3/EVP_EncryptInit.pod

  Log Message:
  -----------
  Update SIV mode documentation

Fixes #18440

Reviewed-by: Shane Lontis <shane.lontis at oracle.com>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18485)