Suggestion: Add Folder example to Assets Guide

The [Dioxus Guide Page](https://dioxuslabs.com/learn/0.6/guides/assets#) for Assets includes explanations and codes snippets for importing images, arbitrary files and StyleSheets.
I suppose this was written with the thought that projects using many images would serve them from back-end (this usually being more user-friendly.)

However, as someone relatively new to Rust and Dioxus with limited resources, setting up a backend is not viable for me. Since the (web) app I am building uses 100s of images, doing 100s of `asset!(...)` calls is ugly, bloat, etc...

Since (after asking) I found out it is easy to import a folder 1st party, I thought it was strange for that part not to be featured in the docs, especially since it is very useful when organizing files, especially for people not used to the rustacean way yet.

### Suggestion:
Add a Folder section to the [Assets guide](https://dioxuslabs.com/learn/0.6/guides/assets), giving a brief explanation of how it works and how to properly implement it in code, as well as a snippet illustrating an example use case.