Add Debezium CDC examples for Postgres & SQL Server & MySQL

[bobbyiliev]

In addition to the updated Debezium v2.x documentation I decided to also add a simple hands-on example so people could also have it as a reference along side the documentation and actually be able to see this in action.

Planning to do the same for SQL server as well once I start working on the docs.

Update 1: Also added a demo for the SQL server so we could have it as a reference.