Wiki documentation update with respect to Gradle

[Jacques Le Roux]

Hi,

I have done some wiki documentation update with respect to Gradle recently. Today I got issues with Confluence which broke my working flow on the 
Apache OFBiz Technical Production Setup Guide <https://cwiki.apache.org/confluence/display/OFBIZ/Apache+OFBiz+Technical+Production+Setup+Guide> page 
more than once. So I'd appreciate reviews, not only on this page but on all recently changed pages. If you follow Confluence changes, you should be 
aware of them.

Thanks

Jacques