config: adding to records/config.py requires a change in records/ext.py

Right now if you update `records/config.py` you also have to remember to add your added/removed config key in `records/ext.py` or else it won't be merged into app config. It would be more convenient and clearer if whatever you configured in `records/config.py` would automatically be added to the app config.

Also regarding the `*_ENDPOINTS_ENABLED` config variable, what's the purpose of it?

Read records/config.py and records/ext.py to trace how configuration keys are merged into the application config. Determine how the *_ENDPOINTS_ENABLED variables are intended to work; done means changes in records/config.py are incorporated automatically without duplicate edits in records/ext.py and the variable purpose is documented or clarified.

Written by the indexing model from the issue text.