[openssl/openssl] 27315a: doc: add the migration guide to the new guide series

[Matthias St. Pierre]

  Branch: refs/heads/master
  Home:   https://github.com/openssl/openssl
  Commit: 27315a978e280a20c7f3ea0bfe05f6c186137625
      https://github.com/openssl/openssl/commit/27315a978e280a20c7f3ea0bfe05f6c186137625
  Author: Matthias St. Pierre <matthias.st.pierre at ncp-e.com>
  Date:   2023-08-23 (Wed, 23 Aug 2023)

  Changed paths:
    M README.md
    M dev/release-aux/openssl-announce-pre-release.tmpl
    M dev/release-aux/openssl-announce-release.tmpl
    M doc/build.info
    M doc/man7/fips_module.pod
    R doc/man7/migration_guide.pod
    M doc/man7/ossl-guide-introduction.pod
    A doc/man7/ossl-guide-migration.pod

  Log Message:
  -----------
  doc: add the migration guide to the new guide series

Reviewed-by: Hugo Landau <hlandau at openssl.org>
Reviewed-by: Matt Caswell <matt at openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21807)