DRILL-4013:JDBC/ODBC Warnings Design Proposal

[Abhijit Pol]

posted initial design proposal for
https://issues.apache.org/jira/browse/DRILL-4013

direct link:
https://docs.google.com/document/d/14d0t6XW6iLKqFpdzmYqpbrHR6-X-jHgM-VjTQwYybao/

please review and provide feedback/comments on the doc.