Doc: Add documentation about the configure options

Task-number: QTBUG-32766
Change-Id: Ie65306b4672c56d05ae693ead1a4c80bc4422342
Reviewed-by: Venugopal Shivashankar <venugopal.shivashankar@digia.com>
Reviewed-by: Topi Reiniö <topi.reinio@digia.com>
Reviewed-by: Martin Smith <martin.smith@digia.com>