Update Doc for Laravel 11 (Role Policy and Custom folder structure)

[paulhenry46]

Update Role Policy and Custom folder structure parts of the Doc following the changes introduced by Laravel 11 in particular those concerning the Service Providers.

[what-the-diff]

PR Summary

• Improved Documentation for RolePolicy Usage
  Instructions have been added to the README file to explain how RolePolicy is used in Laravel 10 and Laravel 11.

• Inclusion of Code Examples for Third-Party Policies
  Code examples have been incorporated to demonstrate how to register policies for third-party plugins and models in Laravel 10 and Laravel 11.

• Updated Code Examples for Registering Policies
  The PR also tackles the registering policies for models in Laravel 11. It specificially updates the code examples to include the \App\Models\Blog\Author and \Ramnzys\FilamentEmailLog\Models\Email classes.

• Note on Role Assignments via Filament Forms
  A significant addition to the documentation is a note explaining how to assign roles to users by leveraging the Select or CheckboxList component from Filament Forms.

[bezhanSalleh]

Thanks