Update readme.md (#38681)

Author: ChenxiJiang333

specification/nginx/resource-manager/readme.md

@@ -120,3 +120,19 @@ These settings apply only when `--tag=package-preview-2025-03-01` is specified o
 input-file:
   - Nginx.NginxPlus/preview/2025-03-01-preview/swagger.json
 ```
+
+# Code Generation
+
+## Swagger to SDK
+
+This section describes what SDK should be generated by the automatic system.
+This is not used by Autorest itself.
+
+``` yaml $(swagger-to-sdk)
+swagger-to-sdk:
+  - repo: azure-sdk-for-python
+```
+
+## Python
+
+See configuration in [readme.python.md](./readme.python.md)