Update download section of README.md
Update download section of README.md

And set Streamlink's URL to streamlink.github.io instead of the repo

bastimeyer/livestreamer-twitch-gui,bastimeyer/livestreamer-twitch-gui,chhe/livestreamer-twitch-gui,streamlink/streamlink-twitch-gui,chhe/livestreamer-twitch-gui,chhe/livestreamer-twitch-gui,bastimeyer/livestreamer-twitch-gui,streamlink/streamlink-twitch-gui,streamlink/streamlink-twitch-gui