Better explanation of the Bevy Scene example

[Arend-Jan]

How can Bevy's documentation be improved?

For me it was not clear enough how the scene example is working. I already made pull request with my suggestions.

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This commit overhauls the documentation in the Bevy scene loading example. It adds thorough explanatory comments to guide new Rust and Bevy developers. The rewritten docs clarify how to:

• Register types for reflection, enabling serialization and dynamic property access
• Skip serializing certain fields with #[reflect(skip_serializing)]
• Use FromWorld for components that require runtime initialization
• Store and serialize Resources in scene files
• Load scenes using a DynamicSceneRoot and handle updates in a system
• Serialize a brand-new scene to a separate file asynchronously using IoTaskPool
• These additions aim to provide a clear, step-by-step reference that demonstrates how to implement a scene-based workflow, making it easier for beginners and experienced developers alike to use Bevy’s scene system effectively.

[Arend-Jan]

solved and merged