Pulsar SQL should based on Trino (previous PrestoSQL) instead of PrestoDB

[tison]

The README.md writes:

If you enable Pulsar SQL, the cluster provides Presto access to the data stored in BookKeeper (and tiered storage, if enabled). Presto is exposed on the service named -sql.

I think it should be clarified as Trino (previous PrestoSQL) with correct link.