Add plugin naming conventions and document rename script

[Rafikooo]

Summary

• Add dedicated section explaining plugin naming conventions (official vs community)
• Document that rename script runs automatically after composer create-project
• Add warning about Plugin suffix requirement for directory name
• Remove Claude/AI assistant hints
• Simplify cleanup step

Plugin Naming Conventions

Official Sylius Plugins

Element	Pattern	Example
Namespace	Sylius\{Feature}Plugin	Sylius\InvoicingPlugin
Package	sylius/{feature}-plugin	sylius/invoicing-plugin

Community Plugins

Element	Pattern	Example
Namespace	{Vendor}\Sylius{Feature}Plugin	Acme\SyliusWishlistPlugin
Package	{vendor}/sylius-{feature}-plugin	acme/sylius-wishlist-plugin