Added missing comma after VS 2017 in README.md (#3285)
Added missing comma after VS 2017 in README.md (#3285)


JoshuaKGoldberg/tslint,JoshuaKGoldberg/tslint,JoshuaKGoldberg/tslint,mprobst/tslint,andy-ms/tslint,palantir/tslint,mprobst/tslint,andy-ms/tslint,andy-ms/tslint,mprobst/tslint,palantir/tslint,palantir/tslint,andy-hanson/tslint,andy-hanson/tslint,andy-hanson/tslint