go to port 80 as per new nginx confi

oh, I didn't know the default nginx conf was set up for this. It might make sense to also change https://github.com/mozilla/marketplace-docs/commit/6c8f46f5ff7f18e8425b923c4a56f54eaaf3f2ea#diff-704418e07b1656d5df0c64dfdfbe44d5R205