Update README.md

versions before v0.9.9 return 400 http errors as of June 2023

Author: navicore

README.md

@@ -84,7 +84,7 @@ resource_types:
   type: docker-image
   source:
     repository: navicore/teams-notification-resource
-    tag: latest
+    tag: v0.9.9
 ```
 
 ## Param Configuration