update readme for 2-1-stable
update readme for 2-1-stable

vulk/spree-account-recurring,vinsol/spree-account-recurring,DeweyBanks/spree-account-recurring,abrambailey/spree-account-recurring2,vinsol/spree-account-recurring,DeweyBanks/spree-account-recurring,wycleffsean/spree-account-recurring,vulk/spree-account-recurring,wycleffsean/spree-account-recurring,stuartbates/spree-account-recurring,ardensol/spree-account-recurring,vulk/spree-account-recurring,tzzzoz/spree-account-recurring,wycleffsean/spree-account-recurring,stuartbates/spree-account-recurring,vinsol/spree-account-recurring,abrambailey/spree-account-recurring2,DeweyBanks/spree-account-recurring,tzzzoz/spree-account-recurring,tzzzoz/spree-account-recurring,ardensol/spree-account-recurring,stuartbates/spree-account-recurring,ardensol/spree-account-recurring