add some information on lyrebird

currently lyrebird is only mentioned in the "antivirus-blocking-tor" page. My understanding is that it is used for obfs4, meek, and possibly circumvention api and requesting moat bridges (though i'm not sure, we'd need confirmation from application and/or ac team), but that isn't really documented anywhere. People who look at what process makes network connections on their systems can get worried about what lyrebird is, and if they find it's the new name of obfs4proxy, why it's making connections despite them not using obfs4