Add a golang tutorial to `BitTorrent Client`

added 
* [**Go**: _Building a BitTorrent client from the ground up in Go_](https://blog.jse.li/posts/torrent/)
to Build your own `BitTorrent Client`

README.md

@@ -62,6 +62,7 @@
 * [**Nim**: _Writing a Bencode Parser_](https://xmonader.github.io/nimdays/day02_bencode.html)
 * [**Node.js**: _Write your own bittorrent client_](https://allenkim67.github.io/programming/2016/05/04/how-to-make-your-own-bittorrent-client.html)
 * [**Python**: _A BitTorrent client in Python 3.5_](http://markuseliasson.se/article/bittorrent-in-python/)
+* [**Go**: _Building a BitTorrent client from the ground up in Go_](https://blog.jse.li/posts/torrent/)
 
 #### Build your own `Blockchain / Cryptocurrency`