It is not user documentation and should not be treated as such.
Documentation is available here.
Vdsm API Schema
I recently took on the large task of fully describing the vdsm API in a schema language. I used the QAPI schema format that is currently used by Qemu. This schema allows us to do some pretty cool things.
* Produce an API document with full cross-referenced type information * Automatically generate source code that can be built into libvdsm (C bindings for the official API) * Formalize the API
Here is a sample of the API documentation we can produce from the schema
Here is the schema file itself