Register a json file for each plugin alongside the config.json (this would need to explicitly disallow naming your plugin "config" and/or throw an error if multiple plugins have the same name)
Pros:
Allows for keeping multiple versions easily (i.e., with plugin versions). Maybe have a compatibleVersions field plugins can check to keep configs backwards compatible.
Cons:
Multiple files. Takes a tiny bit of extra work to do.
Register a new entry in the existing config with a map.
This could be done in two ways:
config.json
(this would need to explicitly disallow naming your plugin "config" and/or throw an error if multiple plugins have the same name)compatibleVersions
field plugins can check to keep configs backwards compatible.