docs: Remove unused Sphinx extension.
docs: Remove unused Sphinx extension.

gravyboat/streamlink,flijloku/livestreamer,Masaz-/livestreamer,chrippa/livestreamer,programming086/livestreamer,Masaz-/livestreamer,flijloku/livestreamer,bastimeyer/streamlink,chhe/streamlink,Klaudit/livestreamer,javiercantero/streamlink,javiercantero/streamlink,caorong/livestreamer,Feverqwe/livestreamer,sbstp/streamlink,wolftankk/livestreamer,programming086/livestreamer,Klaudit/livestreamer,chrippa/livestreamer,chrisnicholls/livestreamer,sbstp/streamlink,lyhiving/livestreamer,chhe/livestreamer,mmetak/streamlink,asermax/livestreamer,blxd/livestreamer,jtsymon/livestreamer,caorong/livestreamer,lyhiving/livestreamer,back-to/streamlink,chhe/streamlink,intact/livestreamer,intact/livestreamer,fishscene/streamlink,gtmanfred/livestreamer,ethanhlc/streamlink,bastimeyer/streamlink,breunigs/livestreamer,chhe/livestreamer,hmit/livestreamer,okaywit/livestreamer,beardypig/streamlink,wlerin/streamlink,wolftankk/livestreamer,Saturn/livestreamer,okaywit/livestreamer,gtmanfred/livestreamer,melmorabity/streamlink,Feverqwe/livestreamer,Dobatymo/livestreamer,jtsymon/livestreamer,fishscene/streamlink,wlerin/streamlink,melmorabity/streamlink,ethanhlc/streamlink,charmander/livestreamer,blxd/livestreamer,back-to/streamlink,hmit/livestreamer,beardypig/streamlink,Dobatymo/livestreamer,Saturn/livestreamer,breunigs/livestreamer,charmander/livestreamer,streamlink/streamlink,derrod/livestreamer,derrod/livestreamer,streamlink/streamlink,gravyboat/streamlink,mmetak/streamlink