Put redirect in place for old arbitration pdf

[cbeams]

No description provided.

[cbeams]

Closing as fixed.

[cbeams]

Before

$ http head https://bisq.io/arbitration_system.pdf
HTTP/1.1 404 Not Found
Age: 1833
Cache-Control: public, max-age=0, must-revalidate
Connection: keep-alive
Content-Encoding: gzip
Content-Length: 118
Content-Type: text/html; charset=utf-8
Date: Tue, 08 Aug 2017 09:43:17 GMT
Etag: 1501750767-ssl-df
Server: Netlify
Vary: Accept-Encoding

After

$ http head https://bisq.io/arbitration_system.pdf
HTTP/1.1 301 Moved Permanently
Age: 0
Cache-Control: public, max-age=0, must-revalidate
Connection: keep-alive
Content-Type: text/plain; charset=utf-8
Date: Tue, 08 Aug 2017 10:15:04 GMT
Location: /docs/arbitration-system.pdf
Server: Netlify