2.0-rc1: Add config option, display path & contents

Two things caused me to want this:

- yaml config:  easier to read, easier to update, less error prone (thus I now have 6 broad-topic jrnl's)
- xdg to locate config;

Besides showing my jrnl's  (`jrnl -ls`), I'd like a reminder of which are encrypted, which are open, what the editor options are to each, and so forth...

If I want to make a change, I'd now (with xdg) need a little help finding the config.

I suppose this could be combined with an edit option (I chose not to, but I could see keeping a backup copy as a useful part, should someone care to do that).