removed assert from README
removed assert from README

jeffbski/joi,tpiecora/joi,rmoorman/joi,opyate/joi,pikselpalette/joi,geminiyellow/joi,cesarmarinhorj/joi,olistic/joi-extended,pandeysoni/joi,davidbenko9/joi,ck-lee/joi,jagoda/joi,bananaoomarang/joi,thethanghn/react-native-joi,lloydbenson/joi,danielb2/joi,robertherber/joi-extended,naitsric/joi