Restore archive_command documentation
Commit
5ef1eefd76f404ddc59b885d50340e602b70f05f, which added
archive_library, purged most mentions of archive_command from the
documentation. This is inappropriate, since archive_command is still
a feature in use and users will want to see information about it.
This restores all the removed mentions and rephrases things so that
archive_command and archive_library are presented as alternatives of
each other.
Reviewed-by: Nathan Bossart <nathandbossart@gmail.com>
Discussion: https://www.postgresql.org/message-id/
9366d634-a917-85a9-4991-
b2a4859edaf9@enterprisedb.com