Codeq is Rich Hickey's proposed framework for documentation generation systems. Because Codeq is based on Datomic, it can support arbitrary queries spanning multiple types and sources of information. The query results can be fed into any desired tools for analysis, visualization, etc.
This flexibility could allow Codeq-based tools to "raise the bar" on documentation systems, providing ways to navigate and understand today's complex, polyglot information systems.
Getting back to the present, Codeq is well worth studying as a Datomic application. In particular, the Codeq schema shows how complicated problem domains (eg, Git repo metadata) can be handled by (relatively) small sets of entities and attributes.