Docs: Add information on the default OpenAPI files available

[JacobCoffee]

Summary

In https://docs.litestar.dev/latest/usage/openapi we don't really specifically say anything about the availability of $openapi_path/openapi.{json,yaml,yml} except in 2 places, 1 of which says it is deprecated:

• https://docs.litestar.dev/latest/usage/openapi/ui_plugins.html#providing-a-subclass-of-openapicontroller (but just glossing over)
• https://docs.litestar.dev/latest/usage/openapi/ui_plugins.html#configuring-the-openapi-root-path (but just glossing over)

It would be nice to document this when people need them e.g., for Scalar API client's collection import feature

[rico33631]

Hi @JacobCoffee! I'd love to work on this issue.

Would you like the documentation to include details about the structure and usage of the default OpenAPI files (openapi.json, openapi.yaml, openapi.yml)? Also, should I highlight how they integrate with tools like Scalar API Client?

[FHU-yezi]

Hi @JacobCoffee! I'd love to work on this issue.

Would you like the documentation to include details about the structure and usage of the default OpenAPI files (openapi.json, openapi.yaml, openapi.yml)? Also, should I highlight how they integrate with tools like Scalar API Client?

IMO I hope we can know about where can we get it, and what will happen if we accidently override it in our code (e.g. defined the same route), intergrating to Scalar etc. is not required while we already got the automatic Scalar API doc, and it will be the default option in 3.0.