Improve errhint for ALTER SUBSCRIPTION ADD/DROP PUBLICATION

Hi,

While working on some logical replication related features.
I found the HINT message could be improved when I tried to add a publication to
a subscription which was disabled.

alter subscription sub add publication pub2;
--
ERROR: ALTER SUBSCRIPTION with refresh is not allowed for disabled subscriptions
HINT: Use ALTER SUBSCRIPTION ... SET PUBLICATION ... WITH (refresh = false).
--

Because I was executing the ADD PUBLICATION command, I feel the hint should
also mention it instead of SET PUBLICATION.

Best regards,
Hou zj