README: add a cute little version tag badge (#4596)
README: add a cute little version tag badge (#4596)


koreader/koreader,NiLuJe/koreader,houqp/koreader,Frenzie/koreader,mihailim/koreader,pazos/koreader,NiLuJe/koreader,Frenzie/koreader,Markismus/koreader,Hzj-jie/koreader,mwoz123/koreader,poire-z/koreader,koreader/koreader,poire-z/koreader