Build time OpenApi in YAML

### Description

update: Generating penAPI documents in YAML format at build time is currently not supported, but planned in a future preview.

### Page URL

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/openapi/aspnetcore-openapi?view=aspnetcore-9.0&tabs=visual-studio%2Cvisual-studio-code

### Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/fundamentals/openapi/aspnetcore-openapi.md

### Document ID

27bad30c-e0b4-10fb-b202-a29d4f8fad24

### Platform Id

11e029f8-4c25-d943-fe65-31bfcaf35e2b

### Article author

@captainsafia

### Metadata

* ID: 27bad30c-e0b4-10fb-b202-a29d4f8fad24
* PlatformId: 11e029f8-4c25-d943-fe65-31bfcaf35e2b
* Service: **aspnet-core**
* Sub-service: **fundamentals**

[Related Issues](https://github.com/dotnet/AspNetCore.Docs/issues?q=is%3Aissue+is%3Aopen+27bad30c-e0b4-10fb-b202-a29d4f8fad24)