Documentation example to list/delete an IMMV

[adamguo0]

Hi, I'm wondering if we can add a documentation example on how to list/delete an IMMV? I think it will help new users to spell it out in the docs.

Something like this to list IMMVs and their queries:

SELECT immvrelid AS immv_oid, get_immv_def(immvrelid) AS immv_def FROM pg_catalog.pg_ivm_immv;

If I understand correctly, to drop an IMMV you just need to drop the table.

DROP TABLE immv;