Add/link updated documentation on packaging and using a finished provider

### What problem are you facing?

While this repository is adequately documented on how to develop your own provider, I feel like we're on our own when it comes to what is needed to package and finalize the provider - both as an open source project available in the Upbound marketplace, and simply making it work with my own Crossplane installation.

### How could Crossplane help solve your problem?

Please review the existing documentation and create an easy to follow path forward, rather than the mix-and-match pieces of information currently available here and there.