docs: fix/add Toast / Custom component example / Razor code

[JarJasAskom]

🙋 Documentation Request

Toast documentation, "Custom component" example.

Toast example contains line:

ToastService.ShowToast<MyToastComponent, MyToastData>(new ToastParameters()

but

Example code does not contain source of MyToastComponent and MyToastData .

💁 Possible Solution

Add MyToastComponent razor code and MyToastData C# code.

[dvoituron]

It would be a good idea to add these files to the documentation.

You can find the code in the GitHub repo and this page in particular.

[vnbaaij]

Fixed in next release. Files added to example