[DOCS] obsolete description for rolreplication in pg_authid and pg_roles

Hi,

catalog.sgml
> That is, this role can initiate streaming replication (see Section
> 26.2.5, “Streaming Replication”) and set/unset the system backup
> mode using pg_start_backup and pg_stop_backup

The latter part of the above description for rolreplication column seems
obsolete because commit 1574783b4ced0356fbc626af1a1a469faa6b41e1
changed pg_start_backup and pg_stop_backup so that GRANT system
is used to manage access to those functions. So I think that we should
get rid of the latter part or replace it with something like "run pg_basebackup
to take a base backup". Thought?

Regards,

--
Fujii Masao