Add documentation about new capturing implementation for the MySQL connector to downstream product

The new capturing implementation for the MySQL connector that was introduced upstream in the 1.5.0.Alpha release with DBZ-1865 is based on the common connector framework used by all of the other Debezium connectors.
In the 1.5 upstream release, the MySQL connector documentation mentions the new implementation in a note that explains that the connector behavior is on par with the previous implementation, save that it does not include the experimental parallel snapshotting feature (DBZ-175), to be reintroduced in a different form in a future version.

Users who encounter issues with the new capturing implementation have the option to revert to the previous implementation.