updated readme.md to package-2021-06-preview (#16110)

Ajit Navasare · web-flow · commit e2ea3a2d0493 · 2021-09-22T11:18:19.000+08:00
diff --git a/specification/servicebus/resource-manager/readme.md b/specification/servicebus/resource-manager/readme.md
@@ -26,7 +26,7 @@ These are the global settings for the ServiceBus API.
 
 ``` yaml
 openapi-type: arm
-tag: package-2018-01-preview
+tag: package-2021-06-preview
 ```
 
 ### Tag: package-2021-01-preview
