Create more "books"

*By "books", I mean the top-level sections in the docs, like Router and CLI.*

Some of the tools discussed in the docs could be reorganized into their respective books. This would reduce duplication and be more organized/coherent. Right now, it feels "scattered".

For example, `Getting started > Web`, `Reference > Web`, `Cookbook > Publishing > Web` could all be unified under a "Web" book. This includes all the other renderers, where each book contains all the steps to publish a project using a specific renderer. Additionally, there should be a guide on how to publish the same app on different platforms.

Every book should have a "Reference" section and an "Example project" section, which showcases elements from the Reference. The Router book has this, but the difference between the two sections should be clear. For example, the Router book example project has a [Navigation Targets](https://dioxuslabs.com/learn/0.4/router/example/navigation-targets) section, but this should be in the Reference, as it's not even included in the final example project code.