[Docs] Getting Started: Rspack & webpack

[jbroma]

Documentation is

• Missing
• Outdated
• Confusing
• Not sure?

Explain in Detail

currently there is only placeholder in v5 docs

Your Suggestion for Changes

• explain the differences
• how to use one or the other (commands setup + config setup)
• link to resources from rspack showing detailed benchmarks

[dougg0k]

Benchmark vs Metro, using rspack 1.2 latest features, would be nice to see.

Including any sort of speed / latency measurement and bundle size.

[jbroma]

@dougg0k actually for the bundle size we already have something here: #581 (comment) (any kind of feedback is most welcome 🙏 )

I guess we could something similar for startup times too