Create a really simple example for people to get started

The current "simple" example does too many things and is confusing for newcomers.

It has a full-cue codebase + Makefile that could be intimidating for new folks.

We should possibly start with a simple cue script and the rest of the stuff as YAML artifacts such that people who know crossplane but not cue have to only deal with that one new thing.

The second example could demonstrate how everything can be done in cue (which is the current `example-simple`) and should also be simplified with inputs from crossplane and cue folks.

We should probably also introduce an `init` subcommand in `fn-cue-tools` to create a skeleton directory structure with a simple example composition included.