Update JDBC to 4.2

A new page which describes the enhancements in the jdbc4.2 has been added. This is the link to the page
http://download.java.net/jdk8/docs/technotes/guides/jdbc/jdbc_42.html

The jdbc 4.2 enhancement is also listed under the enhancements page
http://download.java.net/jdk8/docs/technotes/guides/jdbc/index.html