Update readme with notes containing what version of Firefox is necessary
Update readme with notes containing what version of Firefox is necessary

alexduch/jpm,jsantell/jpm,guyzmuch/jpm,benbasson/jpm,nikolas/jpm,mozilla/jpm,mozilla-jetpack/jpm,matraska23/jpm,benbasson/jpm,jsantell/jpm,jsantell/jpm,rpl/jpm,freaktechnik/jpm,rpl/jpm,mozilla/jpm,freaktechnik/jpm,kkapsner/jpm,freaktechnik/jpm,Medeah/jpm,johannhof/jpm,mozilla-jetpack/jpm,johannhof/jpm,nikolas/jpm,mozilla-jetpack/jpm,alexduch/jpm,kkapsner/jpm,guyzmuch/jpm,johannhof/jpm,benbasson/jpm,guyzmuch/jpm,alexduch/jpm,wagnerand/jpm,Medeah/jpm,kkapsner/jpm,Medeah/jpm,mozilla/jpm,rpl/jpm,wagnerand/jpm,nikolas/jpm,wagnerand/jpm,matraska23/jpm,matraska23/jpm