docs(ai): add "Runpod" as community provider

[TimPietrusky]

Background

• we created an official provider for Runpod and want to add this into the official docs, so that people can see it

Summary

• added the docs on how to use the Runpod AI SDK provider

Manual Verification

• i made sure that the format of the file aligns with all the other providers

Checklist

• Tests have been added / updated (for bug fixes / features)
• Documentation has been added / updated (for bug fixes / features)
• A patch changeset for relevant packages has been added (for bug fixes / features - run pnpm changeset in the project root)
• Formatting issues have been fixed (run pnpm prettier-fix in the project root)
• I have reviewed this pull request (self-review)

Future Work

• updates to the provider (like new models) will be provided in the futute

[nicoalbanese]

Thanks!

[TimPietrusky]

@nicoalbanese thank you so much and sorry for the formatting issue!