create readme.typescript.md (#20884)

Author: kazrael2119

specification/developerhub/resource-manager/readme.md

@@ -51,6 +51,7 @@ This is not used by Autorest itself.
 swagger-to-sdk:
   - repo: azure-sdk-for-go
   - repo: azure-sdk-for-python-track2
+  - repo: azure-sdk-for-js
 ```
 
 ## Python
@@ -64,3 +65,7 @@ See configuration in [readme.go.md](./readme.go.md)
 ## Java
 
 See configuration in [readme.java.md](./readme.java.md)
+
+## TypeScript
+
+See configuration in [readme.typescript.md](./readme.typescript.md)

specification/developerhub/resource-manager/readme.typescript.md

@@ -0,0 +1,12 @@
+## TypeScript
+
+These settings apply only when `--typescript` is specified on the command line.
+Please also specify `--typescript-sdks-folder=<path to root folder of your azure-sdk-for-js clone>`.
+
+``` yaml $(typescript)
+typescript:
+  azure-arm: true
+  package-name: "@azure/arm-devhub"
+  output-folder: "$(typescript-sdks-folder)/sdk/developerhub/arm-devhub"
+  generate-metadata: true
+```