adfc-config is different from faces-config
Faces Config is the controller of your application, it's what make JSF based frameworks work effectively, and it's where you will need to define your own customization like view handlers, converters, validators, etc...
adfc-config is just the main application unbounded Task Flow, which make it a little easier for developers to define their pages and main navigation root inside of it instead of doing it the JSF way and define them in faces config, it also provide additional functionality like defining managed beans which will have much more scopes than the original JSF given the ADF Framework additions, but still at the end it's just an Unbounded Task Flow. Here is the documentation reference about adfc-config.xml