[docs] Document how to enable color on dark mode

[Wimukti]

Preview: https://deploy-preview-29340--material-ui.netlify.app/components/app-bar/#enable-color-on-dark
Close #28962

Summary

• Added a demo in the "Enable Color on Dark" section.
• Added code block showing how the AppBar color behavior in dark mode can be overwritten with enableColorOnDark, for both the following cases
  - Enable color on dark for specific elements via prop
  - Affect all App Bar elements via theme
• The section in the documentation about this: https://mui.com/components/app-bar/#enable-color-on-dark

• I have followed (at least) the PR section of the contributing guide.

[mui-pr-bot]

No bundle size changes

Generated by 🚫 dangerJS against c089bb6

[Wimukti]

@siriwatknp Can you review this?

[oliviertassinari]

I have spent 10 minutes pushing new commits, to simplify the demo.

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As a side note for the maintainers, the DX for creating this demo with a script to build the preview is not this great. I had to run the yarn docs:typescript:formatted script multiple times to settle on a preview that really felt great when reading the docs. It feels slower than before.

[Wimukti]

@oliviertassinari Thank you so much for reviewing the PR.

[Wimukti]

Argos Expected — Waiting for status to be reported is not passing. are there any suggestions to pass that check? I have configured Argos CI to my fork as well.

[siriwatknp]

I have configured Argos CI to my fork as well.

I am not sure about this but normally you don't need to do that. Does it make Argos stuck? @oliviertassinari

[oliviertassinari]

@siriwatknp The CI is running on the branch of @Wimukti's fork material-ui repository. The CI should be running as a PR on this repository instead. It can't work.