Placement of synchronized_standby_slots description in config.sgml

Hi,

synchronized_standby_slots is defined in guc_parameter.dat as part of
the REPLICATION_PRIMARY group and appears under the "Primary Server"
section in postgresql.conf.sample. However, in the documentation
its description is placed under the "Sending Servers" section.

Given this, it seems the description should also be under "Primary Server"
in the documentation. I've attached a patch that moves it there.

Alternatively, if synchronized_standby_slots is intended to be set also
on a standby in cascading replication setups, then the current documentation
placement may be correct, and instead guc_parameter.dat and
postgresql.conf.sample should be updated. My understanding, though,
is that this parameter is normally set only on the primary. Right?

Regards,

-- 
Fujii Masao