add Windows release to README
add Windows release to README

Also bumps the release version to v2.6.1.

technosophos/deployment-manager,michelleN/deployment-manager,technosophos/deployment-manager,fibonacci1729/helm,appscode/helm,adamreese/deployment-manager,helm/helm,fibonacci1729/helm,technosophos/k8s-helm,adamreese/helm,technosophos/k8s-helm,SlickNik/helm,adamreese/deployment-manager,helm/helm,adamreese/helm,technosophos/deployment-manager,eicnix/helm,bacongobbler/helm,jascott1/helm,eicnix/helm,adamreese/deployment-manager,technosophos/deployment-manager,bacongobbler/helm,jascott1/helm,appscode/helm,technosophos/deployment-manager,adamreese/deployment-manager,adamreese/deployment-manager,SlickNik/helm,michelleN/deployment-manager,michelleN/deployment-manager,michelleN/deployment-manager