[Idefics2] Improve docs, add resources (#30717)
* Add resources
* Address comment
* Address comments
* Update docs/source/en/model_doc/idefics2.md
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
* Update figure
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Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
