improve docs in etc/dispersion.conf-sample
improve docs in etc/dispersion.conf-sample

1. add a comment to hint using a new account for using dispersion tools
2. change sample url for keystone from 'saio' to 'localhost'

Change-Id: I4683f5eb0af534b39112f1b7420f67d569c29b3a

matthewoliver/swift,redbo/swift,maginatics/swift,matthewoliver/swift,openstack/swift,bouncestorage/swift,Seagate/swift,revoer/keystone-8.0.0,NeCTAR-RC/swift,hbhdytf/mac2,Em-Pan/swift,clayg/swift,iostackproject/IO-Bandwidth-Differentiation,AfonsoFGarcia/swift,smerritt/swift,clayg/swift,thiagodasilva/swift,zackmdavis/swift,eatbyte/Swift,nadeemsyed/swift,nadeemsyed/swift,aerwin3/swift,Khushbu27/Tutorial,revoer/keystone-8.0.0,redhat-openstack/swift,Seagate/swift,swiftstack/swift,psachin/swift,levythu/swift,swiftstack/swift,williamthegrey/swift,hurricanerix/swift,rackerlabs/swift,openstack/swift,psachin/swift,scality/ScalitySproxydSwift,scality/ScalitySproxydSwift,IPVL/swift-kilo,hurricanerix/swift,swiftstack/swift,redbo/swift,eatbyte/Swift,smerritt/swift,takeshineshiro/swift,Akanoa/swift,anishnarang/gswift,nadeemsyed/swift,mjzmjz/swift,wenhuizhang/swift,matthewoliver/swift,bradleypj823/swift,larsbutler/swift,mjwtom/swift,xiaoguoai/ec-dev-swift,shibaniahegde/OpenStak_swift,smerritt/swift,bkolli/swift,psachin/swift,clayg/swift,anishnarang/gswift,hurricanerix/swift,Khushbu27/Tutorial,bradleypj823/swift,hbhdytf/mac,Em-Pan/swift,wenhuizhang/swift,tipabu/swift,psachin/swift,tipabu/swift,bkolli/swift,dencaval/swift,openstack/swift,hbhdytf/mac2,hbhdytf/mac2,bouncestorage/swift,iostackproject/IO-Bandwidth-Differentiation,Akanoa/swift,daasbank/swift,gold3bear/swift,rackerlabs/swift,gold3bear/swift,levythu/swift,notmyname/swift,williamthegrey/swift,shibaniahegde/OpenStak_swift,notmyname/swift,hbhdytf/mac,larsbutler/swift,zackmdavis/swift,matthewoliver/swift,IPVL/swift-kilo,tipabu/swift,prashanthpai/swift,sarvesh-ranjan/swift,hurricanerix/swift,hbhdytf/mac2,thiagodasilva/swift,clayg/swift,maginatics/swift,openstack/swift,AfonsoFGarcia/swift,xiaoguoai/ec-dev-swift,daasbank/swift,notmyname/swift,aerwin3/swift,tipabu/swift,nadeemsyed/swift,dpgoetz/swift,NeCTAR-RC/swift,mjwtom/swift,redhat-openstack/swift,smerritt/swift,sarvesh-ranjan/swift,prashanthpai/swift,dencaval/swift,mjzmjz/swift,notmyname/swift,dpgoetz/swift,takeshineshiro/swift