README add browser support
README add browser support

Added a description of the browsers supported, and change future plans about previous protocol version support.
kofidazy/PHP-Websockets,jahanzaibbahadur/PHP-Websockets,sjw-github/PHP-Websockets,ghedipunk/PHP-Websockets,vinod1988/PHP-Websockets,jerinho/PHP-Websockets,philek/PHP-Websockets,jerinho/PHP-Websockets,jahanzaibbahadur/PHP-Websockets,Xaraknid/PHP-Websockets,zjsxwc/PHP-Websockets,sjw-github/PHP-Websockets,kofidazy/PHP-Websockets,philek/PHP-Websockets,Xaraknid/PHP-Websockets,ghedipunk/PHP-Websockets,zjsxwc/PHP-Websockets,vinod1988/PHP-Websockets