msi for asc (#870)

* msi for asc

* add a period

* move asc before app service

* remove space

* system-assigned

Co-authored-by: Guoqing Geng <hellokangning@hotmail.com>
Co-authored-by: Guoqing Geng <gugeng@microsoft.com>
Co-authored-by: Xiaolu Dai <31124698+saragluna@users.noreply.github.com>

azure-spring-boot-starters/azure-keyvault-secrets-spring-boot-starter/README.md

@@ -33,6 +33,14 @@ azure.keyvault.secret.keys=key1,key2,key3
 ```
 
 ### Use MSI / Managed identities 
+#### Azure Spring Cloud
+
+Azure Spring Cloud supports system-assigned managed identity only at present. To use it for Azure Spring Cloud apps, add the below properties:
+```
+azure.keyvault.enabled=true
+azure.keyvault.uri=put-your-azure-keyvault-uri-here
+```
+
 #### App Services
 To use managed identities for App Services - please refer to [How to use managed identities for App Service and Azure Functions](https://docs.microsoft.com/en-us/azure/app-service/app-service-managed-service-identity).