storage.quota.enforced is documented in the 2.6. Configuration File Options docs: http://docs.mongodb.org/manual/reference/configuration-options/#storage.quota.enforced

I believe this implies that I should be able to use this option in a YAML config file.

However, the code defines this as a legacy-only option:

https://github.com/mongodb/mongo/blob/v2.6/src/mongo/db/mongod_options.cpp#L196

Not sure who is correct, please just move this to DOCS if its just a documentation blooper.