Customizable dest path and basic secrets (sops)

Can specify where to put the rendered templates, relative to config roots
Can specify to encrypt a subset of the files using sops (requires sops installed locally), but not a great solution yet

Docs and maintenance

Docs, diagrams, refactor some code

first release

This is the first release of terraform-local-gen-files.

For the next while, anything could change, even the name of the repo!