readme: add getAnnounceOpts
readme: add getAnnounceOpts

jamesliu96/webtorrent,yciabaud/webtorrent,rom1504/webtorrent,webtorrent/webtorrent,webtorrent/webtorrent,arestov/webtorrent,jamesliu96/webtorrent,yciabaud/webtorrent,feross/webtorrent,joshterrill/webtorrent,joshterrill/webtorrent,feross/webtorrent