All documentation is included in the CBA release package.
The functions library reference can be shown in-game via a simple function call (requires CBA). This is a copy of the information available in the documentation provided in the release package or online (however, the online reference might have extra or corrected information in):1 call BIS_fnc_help
All CBA functions are, not unsurprisingly, under the CBA section (select configFile and CBA in top left lists).
Equivalent information can be found in the online documentation.