update readme

Signed-off-by: Markus Blaschke <mblaschke82@gmail.com>

Author: mblaschke

README.md

@@ -26,7 +26,11 @@ Help Options:
  -h, --help Show this help message
 ```
 
-for Azure API authentication (using ENV vars) see https://docs.microsoft.com/en-us/azure/developer/go/azure-sdk-authentication
+
+for Azure API authentication (using ENV vars)
+see https://docs.microsoft.com/en-us/azure/developer/go/azure-sdk-authentication
+
+For AzureCLI authentication set `AZURE_AUTH=az`
 
 ### Configuration file