Add section on service worker caching

[carolhmj]

Looking at this issue: https://forum.babylonjs.com/t/gltf-file-cache-not-updating/12656, I think it could be interesting to have a section on the caching page: https://doc.babylonjs.com/divingDeeper/scene/optimizeCached dedicated to service workers. Seems like they are the recommended solution for caching file-based content, in which our models would fall into: https://web.dev/storage-for-the-web/.

[PirateJC]

@carolhmj - Is this still relevant? Something we should still consider doing?

[KennyStanleyJr]

I think so 🤓 @PirateJC

[thomlucc]

Closing as it is not Babylon specific but more pure javascript