fix documentation for volumes mapping
fix documentation for volumes mapping

Change-Id: If6d5f94237056d3b470c193fdfbcca8d6e86e963

huntxu/fuel-web,koder-ua/nailgun-fcert,eayunstack/fuel-web,nebril/fuel-web,prmtl/fuel-web,SmartInfrastructures/fuel-web-dev,zhaochao/fuel-web,SmartInfrastructures/fuel-web-dev,eayunstack/fuel-web,eayunstack/fuel-web,koder-ua/nailgun-fcert,zhaochao/fuel-web,nebril/fuel-web,zhaochao/fuel-web,eayunstack/fuel-web,SmartInfrastructures/fuel-web-dev,huntxu/fuel-web,nebril/fuel-web,SmartInfrastructures/fuel-web-dev,stackforge/fuel-web,huntxu/fuel-web,stackforge/fuel-web,nebril/fuel-web,stackforge/fuel-web,nebril/fuel-web,prmtl/fuel-web,SmartInfrastructures/fuel-web-dev,huntxu/fuel-web,koder-ua/nailgun-fcert,eayunstack/fuel-web,zhaochao/fuel-web,koder-ua/nailgun-fcert,prmtl/fuel-web,huntxu/fuel-web,prmtl/fuel-web,zhaochao/fuel-web,prmtl/fuel-web