Document Non-default Key Location in README

[EarthCitizen]

I don't see anything in the README that gives an example of an application using other than the default key location. /var/conf/encrypted-config-value.key is a bit too obvious for hackers, so many will likely want to use a more obfuscated name. Perhaps an example configuration can be added for consuming a key in a non-default location?

[EarthCitizen]

Generally an example project showing the correct dependency names to pull in, and from where, would be great.