Currently there are two documents: the main Flora-2 manual and a manual describing the packages that are not part of the core system, but are important additions and are distributed with the system. There is also a tutorial that covers the main aspects of the theory behind Flora-2 as well as introduces the key features of the system.
The LaTeX source files of the Documentation are available from the source code repository. You need LaTeX and the associated tools in order to create a printable version.
Furthermore, Ergo tutorials on the Coherent Knowledge's Web site are also relevant. The Ergo Suite tutorial is a gentle introduction to many syntactic and semantic features of Ergo, and much of it is applicable to Flora-2. The second tutorial, Capturing Real World Knowledge in Ergo, explains the process of development of a knowledge base for a real world domain (the laws from California Driver's Handbook). Almost all of it, including the supplementary materials, applies to Flora-2 as well. This tutorial uses only the basic features of Ergo and Flora-2, and could serve as a good introduction into the subject.