Provide a brief introduction

Author: candleindark

docs/21_models.md

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 # DANDI Models
 
+**DANDI’s metadata models** are defined as [Pydantic models](https://github.com/dandi/dandi-schema/blob/master/dandischema/models.py) in [**dandischema**](https://github.com/dandi/dandi-schema) and transformed into [JSON schemas](https://github.com/dandi/schema). **Both** representations, the original Pydantic definitions and JSON schemas, are used across the DANDI ecosystem. The diagram below outlines how these two representations are defined, generated, and integrated into various components, including the CLI, the backend/API, and the web interface.
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+For more information, follow the links in the diagram to the respective repositories and files.
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 ``` mermaid
 ---
 config: