Support For Multiple Docs

#### Problem
As the number of projects directly maintained by Dioxus Labs increases, it will soon be time to look into adding documentation and pages meant for projects other than the core Dioxus repository.

#### Implementation
I am unsure if the current supporting code needs to be updated to support these changes; however, I suggest a new "Docs" landing page. This page would act as a central hub for finding the documentation you're looking for.

I can aid in the design and development of this page and if required, any upgrades to the supporting code (with some direction).

The issue mentions a new "Docs" landing page but names no files, tests, or entry points. Start by mapping the existing documentation pages and supporting code, then define how multiple projects should be represented; done means the agreed hub lets users find each project's documentation.

Written by the indexing model from the issue text.