Update DynamicReports URL

The original link has been dead for about a year ( https://community.jaspersoft.com/questions/1100606/dynamicreportsorg-offline ).
A WaybackMachine page ( http://web.archive.org/web/20180224203351/http://dynamicreports.org/documentation/documentation-overview ) has a link to a sourceforce page ( https://sourceforge.net/projects/dynamicreports/files/ ), that is dead and has a link to this github page.