Add free-torrents.md
Add free-torrents.md

This markdown file provides a list of the sample torrents built into
WebTorrent Desktop, but with the following improvements:

- working trackers
- all web seeds now hosted on webtorrent.io
- cleaned up files (no useless archive.org metadata)
- added multi-language subtitle files, where available
- magnet links include &xs= property linking to torrent file, so they
can work even when there are no peers

jamesliu96/webtorrent,feross/webtorrent,joshterrill/webtorrent,joshterrill/webtorrent,feross/webtorrent,webtorrent/webtorrent,jamesliu96/webtorrent,webtorrent/webtorrent