Restructure docs around how-to, reference, tutorials, and explanation #72
Description
Aside from the command-line reference, most of the documentation is under "Guides", and this is in danger of becoming a miscellaneous (and therefore not very helpful) classification. To give visitors a better chance of finding what they need, I suggest following the scheme now described at https://documentation.divio.com/introduction/; that is, to structure documentation around the four categories:
- how to guides show people how to accomplish a specific, practical task; e.g., how to migrate to the Helm controller
- reference materials let people look up the details of a command or API, e.g., what the flags are for
flux create image - tutorials aim to teach an aspect of the system, by giving people a step by step guide; e.g., the source-watcher dev guide
- explanations discuss a topic related to the system, so people can get a better understanding of it; e.g., "Core Concepts"
This gives a meaningful first dispatch point for docs visitors -- if they have a specific problem to solve, they can look under "how to", if they want to learn more by doing, they can follow a tutorial, and so on.