Point to supported versions in connector pages

The page https://debezium.io/releases/ is the authoritative source for documenting which database versions are supported by the different Debezium connectors (upstream). At the beginning of each connector docs page, there should be a link to this page:

Please refer to the Debezium release overview for the complete list of <database name> versions supported by this connector.

In particular, this information should not be duplicated on docs pages themselves, as e.g. currently is the case for the Postgres connector.