Add Flight JDBC Connection String example

I have tried to connect using the [JDBC driver](https://arrow.apache.org/docs/java/flight_sql_jdbc_driver.html) added to my Intellij IDEA, with a different combinations of parameters. The driver failed with:

`org.apache.arrow.driver.jdbc.shaded.org.flight.FlightRuntimeException: UNAVAILABLE io Exception`

Any help would be highly appreciated

Review the linked Flight SQL JDBC driver documentation and the existing issue discussion, then reproduce the connection attempt in IntelliJ IDEA using the reported parameter combinations. Done means the repository includes a clear Flight JDBC connection-string example that addresses the reported setup and failure.

Written by the indexing model from the issue text.