Improve readme of depth_guided_stable_diffusion example

[BirgerMoell]

What

• Replaces Improve readme of depth_guided_stable_diffusion example #5502

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• I have read and agree to Contributor Guide and the Code of Conduct
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[Wumpf]

I pushed a blueprint for this example earlier today, so this has now a slight merge conflict with that.

[github-actions]

Size changes

Name	main	5593/merge	Change
re_sdk --no-default-features	117 crates	111 crates	-6 crates

[Wumpf]

there's some deeper conflicts with the blueprint that landed by now for this example that need to be reconciled.

Readme reads well overall but more as a general observation I'm missing on a bunch of things why it would be useful to look at some of the data in particular. Don't think it makes sense to point that out everywhere in detail, but I think it would be nice to point out some of the ways it can be helpful to see what's going on and how one could react to that 🤔. Might be more applicable to other examples