Update README.md to show deploy host OSes supported

Author: bertiethorpe

README.md

@@ -27,6 +27,12 @@ It is recommended to check the following before starting:
 
 ## Installation on deployment host
 
+Current Operating Systems supported to be deploy hosts:
+
+- Rocky Linux 9
+- Rocky Linux 8
+- Ubuntu 22.04
+
 These instructions assume the deployment host is running Rocky Linux 8:
 
     sudo yum install -y git python38