[openssl/openssl] 84eace: Clarify the change of enc -S behavior in 3.0

[openssl-machine]

  Branch: refs/heads/openssl-3.0
  Home:   https://github.com/openssl/openssl
  Commit: 84eace37362913bc091069dbdefdd798e91982f2
      https://github.com/openssl/openssl/commit/84eace37362913bc091069dbdefdd798e91982f2
  Author: Viktor Dukhovni <openssl-users at dukhovni.org>
  Date:   2023-01-26 (Thu, 26 Jan 2023)

  Changed paths:
    M doc/man1/openssl-enc.pod.in

  Log Message:
  -----------
  Clarify the change of enc -S behavior in 3.0

Fixes  #19730

Reviewed-by: Paul Dale <pauli at openssl.org>
Reviewed-by: Shane Lontis <shane.lontis at oracle.com>
Reviewed-by: Tomas Mraz <tomas at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/19732)

(cherry picked from commit a4aa977d3a8049d5386dc583e16c17727c712eaa)