Exchange pages

The idea is to create a page under handshake.org domain (/exchanges ?) and list the exchanges that supports HNS.
Any exchange could be welcome to make a PR to this repo adding themselves.
The effort to check if the exchanges really lists HNS would be minimal.

The page should include a disclaimer, letting visitors know that Handshake.org is not affiliated, sponsor or recommending none of the exchanges, but offering them a public space for listing themselves.

This could be used when new joiners asks where they can buy HNS, better then sending them to coinmarketcap or coingecko, we could refer them an official link.