Create page: /contracts/SynthetixDebtShare

[409H]

This page is located in the SDS contract, line 15, however it resolves to a 404

$ curl -Is  https://docs.synthetix.io/contracts/SynthetixDebtShare | grep HTTP

HTTP/2 404 

Proposal: Create the docs page to describe SDS, even if a stub page so that it does not resolve to a 404.