Don't prefill config files

[kencx]

keyb creates a default config file that contains prefilled configuration. If a new configuration key is added in the future or an existing one is modified, users can easily miss them if they don't read the release notes.

Instead, create a default file in the same location pointing to the documentation.

Reference

[kencx]

Seems like I forgot that a default config file is already not created as of ec73943