Rename config options "mount-dir" and "data-dir"?

[markuswustenberg]

I think it could be worthwhile to reconsider the naming for the mount-dir and data-dir configuration options. In the litefs-example repo, the following values are set:

mount-dir: "/data"
data-dir: "/mnt/data"

So mount-dir has "data" in the value, and data-dir has "mnt" in the value. It makes sense because both directories are mounted and both have data, but which is which seems rather arbitrary, and IMO confusing.

Maybe better names would be access-dir for where LiteFS accesses the db through FUSE, and volume-dir for where the persistent volume is mounted? Or something like that.