Add docs how-to build ISO from gerrit patches
Add docs how-to build ISO from gerrit patches

CI retest

Change-Id: I91b9caafb17ec172b6cd8ab9639d013deea0755a
Signed-off-by: Bogdan Dobrelya <0b23cd1e586d5f091fecb3391314c2b9ec1fd641@mirantis.com>

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