Add a readme for text and vision convert script modal type

[karan6181]

Description of changes:

• Add a readme for NLP and CV convert script modal type.
• Update the conversion scripts with method comments.

Issue #, if available:

CO-1677

Merge Checklist:

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• I have read the contributor guidelines
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[bandish-shah]

Made some minor grammatical and wording nits. Will leave it up to @knighton to sign off on functionality.

[bandish-shah]

Would it also be possible to link to the README's on the docs site? My impression is that these examples are nested in the streaming package and it's not obvious where to find them without digging. We may want to eventually consider up-leveling the conversion scripts in the repo, it doesn't really make sense to have these scripts in the package unless users can invoke them through the streaming API for conversion.

[karan6181]

Would it also be possible to link to the README's on the docs site? My impression is that these examples are nested in the streaming package and it's not obvious where to find them without digging. We may want to eventually consider up-leveling the conversion scripts in the repo, it doesn't really make sense to have these scripts in the package unless users can invoke them through the streaming API for conversion.

Yes, valid point. I have added a short and concise doc dataset_conversion_to_mds.md that references the readme.

[bandish-shah]

👍