pg_create_logical_replication_slot returns text instead of name

Hi,

The documentation[1] says that both pg_create_logical_replication_slot
and pg_create_physical_replication_slot returns slot_name as a name
type. But only pg_create_logical_replication_slot returns it as text
type. I think these should be united as the name type. Attached small
patch fixes it.

[1] https://www.postgresql.org/docs/devel/static/functions-admin.html#FUNCTIONS-REPLICATION

Regards,

--
Masahiko Sawada
NIPPON TELEGRAPH AND TELEPHONE CORPORATION
NTT Open Source Software Center