[Docs RFC] update the live sync doc to add a user with replication rights.

[billy-the-fish]

CREATE USER timescale_livesync PASSWORD 'livesync1234';
GRANT USAGE ON SCHEMA "public" TO timescale_livesync;
GRANT SELECT ON ALL TABLES IN SCHEMA "public" TO timescale_livesync;
ALTER DEFAULT PRIVILEGES IN SCHEMA "public" GRANT SELECT ON TABLES TO timescale_livesync;

GRANT rds_replication TO timescale_livesync;
GRANT CREATE ON DATABASE postgres to timescale_livesync;

-- Do the following on all the tables which should be livesynced
ALTER TABLE <table_1> OWNER TO timescale_livesync;
ALTER TABLE <table_2> OWNER TO timescale_livesync;