API documentation format/location

[stuarteberg]

Client libraries that wrap or heavily use DVID endpoints should mention (in their own documentation) which DVID endpoints they are wrapping/using. To that end, it would be nice if they could include links to the DVID documentation for various endpoints.

The DVID API is extensively documented via .../api/help, but there are couple of issues with the current scheme:

1. At the moment, the dvid docs are self-hosted by each DVID server. It would be nice if we hosted a copy of them in a permanent location, so that other projects could link to them.
2. The docs are plaintext, so it is not currently possible to link to specific sections (e.g. for a particular endpoint)