fix typo on CONTRIBUTING.md (#14536)
fix typo on CONTRIBUTING.md (#14536)


apache/incubator-superset,zhouyao1994/incubator-superset,mistercrunch/panoramix,airbnb/caravel,airbnb/caravel,apache/incubator-superset,zhouyao1994/incubator-superset,apache/incubator-superset,airbnb/caravel,airbnb/caravel,mistercrunch/panoramix,mistercrunch/panoramix,mistercrunch/panoramix,zhouyao1994/incubator-superset,apache/incubator-superset,zhouyao1994/incubator-superset,zhouyao1994/incubator-superset,apache/incubator-superset