Add note about Firefox support
Add note about Firefox support

Signed-off-by: Raul Metsma <8b52b6b714585648fd300da0dbc0fa0678553280@metsma.ee>
open-eid/chrome-token-signing,open-eid/chrome-token-signing,metsma/chrome-token-signing,metsma/chrome-token-signing,metsma/chrome-token-signing,metsma/chrome-token-signing,metsma/chrome-token-signing,open-eid/chrome-token-signing,open-eid/chrome-token-signing,open-eid/chrome-token-signing