documentation: [grok usecase] Image inputs and Captioning

[priyansh4320]

Why are these changes needed?

Another Grok Use Case for Image inputs with solution architect agent architecture.

Related issue number

Checks

• I've included any doc changes needed for https://docs.ag2.ai/. See https://docs.ag2.ai/latest/docs/contributor-guide/documentation/ to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[priyansh4320]

Please wait on merge.

[Lancetnik]

@qingyun-wu sorry for bother you, but hwo should review notebooks to merge them to the doc?

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
see 30 files with indirect coverage changes

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[marklysze]

Is this the right description for the notebook?

[marklysze]

can we add some more tags around what the notebook is about, e.g. "image", "multimodal", etc.