doc: update supported branches on README (2.20.x)#12099

greg0ire merged 1 commit intodoctrine:2.20.xdoctrine/orm:2.20.xfrom

alexislefebvre:2.20.x-update-supported-branches-on-READMEalexislefebvre/doctrine-orm:2.20.x-update-supported-branches-on-READMECopy head branch name to clipboard