Fixed typo in README
Fixed typo in README

alanmcruickshank/superset-dev,BRD-CD/superset,apache/incubator-superset,jeromecn/caravel_viz_full,georgeke/caravel,SingTel-DataCo/incubator-superset,apache/incubator-superset,BRD-CD/superset,wbsljh/caravel,alanmcruickshank/superset-dev,SingTel-DataCo/incubator-superset,francisliyy/caravel-aidp,jeromecn/caravel_viz_full,thebucknerlife/caravel,airbnb/superset,dmigo/incubator-superset,BRD-CD/superset,woel0007/caravel,massgov/incubator-superset,SingTel-DataCo/incubator-superset,massgov/incubator-superset,airbnb/caravel,thebucknerlife/caravel,dmigo/incubator-superset,tienhv/caravel,nekia/incubator-superset-dev,airbnb/superset,francisliyy/caravel-aidp,zhouyao1994/incubator-superset,asdf2014/superset,wbsljh/caravel,georgeke/caravel,jeromecn/caravel_viz_full,thebucknerlife/caravel,ArijanaBrlek/superset,mistercrunch/panoramix,mistercrunch/panoramix,zhouyao1994/incubator-superset,airbnb/caravel,airbnb/caravel,airbnb/superset,ArijanaBrlek/superset,woel0007/caravel,tienhv/caravel,timifasubaa/incubator-superset,giaosudau/caravel,asdf2014/superset,woel0007/caravel,massgov/incubator-superset,tienhv/caravel,nekia/incubator-superset-dev,wbsljh/caravel-aidp,zhouyao1994/incubator-superset,asdf2014/superset,wbsljh/caravel-aidp,apache/incubator-superset,BRD-CD/superset,SingTel-DataCo/incubator-superset,giaosudau/caravel,nekia/incubator-superset-dev,alanmcruickshank/superset-dev,francisliyy/caravel-aidp,wbsljh/caravel-aidp,dmigo/incubator-superset,wbsljh/caravel,timifasubaa/incubator-superset,giaosudau/caravel,robert-digit/superset,wbsljh/caravel,airbnb/caravel,jeromecn/caravel_viz_full,robert-digit/superset,apache/incubator-superset,massgov/incubator-superset,georgeke/caravel,francisliyy/caravel-aidp,FrederichCheng/incubator-superset,georgeke/caravel,giaosudau/caravel,alanmcruickshank/superset-dev,timifasubaa/incubator-superset,apache/incubator-superset,nekia/incubator-superset-dev,mistercrunch/panoramix,tienhv/caravel,mistercrunch/panoramix,asdf2014/superset,woel0007/caravel,robert-digit/superset,ArijanaBrlek/superset,zhouyao1994/incubator-superset,FrederichCheng/incubator-superset,zhouyao1994/incubator-superset,thebucknerlife/caravel,dmigo/incubator-superset,timifasubaa/incubator-superset,airbnb/superset,ArijanaBrlek/superset,FrederichCheng/incubator-superset,robert-digit/superset,wbsljh/caravel-aidp,FrederichCheng/incubator-superset