Update Yarn version in README
Update Yarn version in README
JoshuaKGoldberg/tslint,berickson1/tslint,berickson1/tslint,JoshuaKGoldberg/tslint,andy-hanson/tslint,JoshuaKGoldberg/tslint,mprobst/tslint,IllusionMH/tslint,palantir/tslint,mprobst/tslint,IllusionMH/tslint,mprobst/tslint,andy-hanson/tslint,andy-hanson/tslint,palantir/tslint,andy-ms/tslint,berickson1/tslint,andy-ms/tslint,palantir/tslint,IllusionMH/tslint,andy-ms/tslint