Not sure we should be bailing out of the loop here. I'll admit it's a bit weird, but technically it should work fine to have a `[hekad]` section spread across multiple files; if any value is defined more than once then the last one evaluated will be chosen. Go's `ioutil.ReadDir` always lists the files in the same (alphabetical) order, so the same config will always produce the same result.

This would match the behavior of the rest of the config sections; there's nothing preventing someone from putting the same section title in two different files, and currently the code would load them in order, merging them into one config, with values from the later files "winning" over values from earlier ones in cases of conflict.

This might even become a useful testing and debugging tool. Users could temporarily add a "zzz.toml" file where they overwrite config that was defined earlier; deleting the file would return the config to its original condition.