mention Linux and OSX support (or lack of) with detail

[Olm-e]

hello,
the website is lacking details on diverse platforms
it specifically lacks info on OSX and GNU-Linux (and derivative) systems
it is necessary to mention them for

• the public that seeks info to see what the status is and not be mislead by the media titles
• the developers to see and make them able to either help/contribute or even have a bit of overview for their future developments.

additional information toward specific issues and last development are a +
(eg for firefox : add link to https://bugzilla.mozilla.org/buglist.cgi?quicksearch=[webvr] )

I can try to make a PR with info for Linux that I have (I'm just a quidam trying to make it work for my own webvr dev... not related to any org ... ;) ) ...

better if you start it with Chrome(ium) info and some add FF later
tks