Improve the release story

Our release story atm isn't brilliant, is effectively undocumented, and is different to what I do elsewhere so I get confused every time I do it. We currently have no ability to push pre-release nuget packages, and making a release is a multi-step operation.

Where I think I'd like to get to is:

• Create a release in Github, configuring the version number (including pre-release suffixes) as a new Tag when saved.
  • And release notes etc etc
• Release pipeline runs automatically on new tag/new release to Build and push the release
• Release Pipeline is the same as the CI build, but actually pushes artifacts (containers, nugets etc) downstream
  • Put another way, I want as much of the release pipeline run as CI as possible, so the CI can catch as many issues as possible
  • I'm probably ok with skipping the tests in the Release pipeline because they are all run on PR/CI builds
• Light docco item explaining this process for future peeps

I might get a chance to play with this over the next day or two, otherwise it will a couple of weeks before my next chance... if anyone else has feedback/opinions, or wants to contribute please join in the conversation.