[README] use a numbered list instead of bullets for org list (#6629)
[README] use a numbered list instead of bullets for org list (#6629)

* [README] use a numbered list instead of bullets for org list

* Add companies frmo https://stackshare.io/superset/in-stacks

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