Add Use Statements in the Guide

## Feature Request

Going through the guide it doesn't show any use statements to bring items into scope. This means when you enter the code it you just get errors saying `dioxus_thing` is undeclared.

Code in the Guide:

Error:

Code in the Guide:

Errors:

After adding use statement:

Have to add another use statement:

## Implement Suggestion
Show relevant use statements to the code provided in the guide.