Update readme.md to show up documentation for preview version (Azure#29165)

Author: raghumunukutla

specification/support/resource-manager/readme.md

@@ -26,7 +26,7 @@ These are the global settings for the Support API.
 
 ``` yaml
 openapi-type: arm
-tag: package-2024-04
+tag: package-preview-2023-06
 ```