Add note about support for 1.4
Add note about support for 1.4

FirebaseExtended/angularfire,douglascorrea/angularfire,itxd/angularfire,douglascorrea/angularfire,jamestalmage/angularfire,bpietravalle/angularfire,yoda-yoda/angularfire,FirebaseExtended/angularfire,cesarmarinhorj/angularfire,nbr1ninrsan2/angularfire,itxd/angularfire,nbr1ninrsan2/angularfire,jamestalmage/angularfire,itxd/angularfire,yoda-yoda/angularfire,jamestalmage/angularfire,yoda-yoda/angularfire,bpietravalle/angularfire,nbr1ninrsan2/angularfire,fbentz/angularfire,bpietravalle/angularfire,douglascorrea/angularfire,cesarmarinhorj/angularfire,denisKaranja/angularfire,fbentz/angularfire,fbentz/angularfire,denisKaranja/angularfire,cesarmarinhorj/angularfire,denisKaranja/angularfire,FirebaseExtended/angularfire