[openssl/openssl] a7c54d: add note about retrieving error stack

[Vladimir Kotal]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: a7c54dde5189f11c046f638e5aaf2004aee34202
      https://github.com/openssl/openssl/commit/a7c54dde5189f11c046f638e5aaf2004aee34202
  Author: Vladimír Kotal <vladimir.kotal at oracle.com>
  Date:   2023-06-26 (Mon, 26 Jun 2023)

  Changed paths:
    M doc/man3/SSL_get_verify_result.pod

  Log Message:
  -----------
  add note about retrieving error stack

Reviewed-by: Tomas Mraz <tomas at openssl.org>
Reviewed-by: Paul Dale <pauli at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21220)