The Toolkit version of jsPlumb has the Community version as a dependency. These docs refer to version 2.3.0 of the Toolkit edition, and version 2.15.0 of the Community edition.
This site provides the documentation for the Toolkit edition. For Community edition documentation, visit this page.
The best place to get started familiarising yourself with the architecture of the Toolkit is to read through the
documentation on one of the example applications - either the Database Visualizer or the
Flowchart Builder. Then, with your licensed copy of the Toolkit, you can
use Grunt to create a clone of one of these apps and start hacking away.
Alternatively, you might like to start with the documentation. The Data Model and Basic Concepts
pages are the best places to start looking around. In a nutshell, the Toolkit uses a directed graph as
its core data structure. Every app that has a need for jsPlumb - which is to say a need for the ability to connect
entities - can be thought of in terms of a directed (or undirected) graph.