Full documentation is available in the official PBS Pro Guides.
There is no separate documentation that is solely focused on the open source licensed version. Although these guides are focused on the commercially-licensed version of PBS Pro, they fully document the open source licensed version as well. The open source licensed and commercially licensed versions share the same features except as noted below:
Only available with the commercially licensed release:
Changes in the open source release (as of 14.1):
See the /wiki/spaces/~agurban/pages/6193157 for future enhancement plans.