api: document new API changes before releasing

[kilpatty]

Currently HNScan is running on a new version of our API that drastically speeds up the response times. This API is currently hosted at beta.urkellabs.com. Our old version of the API is at api.hnscan.com. We have a number of people who rely on api.hnscan.com and therefore should be very careful about introducing changes into the API without documenting them.

We need to release our API docs before upgrading the API and then make it very clear and where and when the upgrade will occur.