Sharding-JDBC 2.x example.

Example for 1.x please see tags in https://github.com/shardingjdbc/sharding-jdbc/tree/${tag}/sharding-jdbc-example

Example docs please see :
    EN : http://shardingjdbc.io/docs_en/01-start/code-demo/
    CN : http://shardingjdbc.io/docs_cn/01-start/code-demo/