Update docker image version in README.md

Signed-off-by: Qi Zhang <[email protected]>

README.md

@@ -101,10 +101,10 @@ This project supports below scenarios for end-to-end guest operating system vali
 This compatible guest operating systems list is used for this project only. For guest operating system support status on ESXi, please refer to [VMware Compatibility Guide](https://www.vmware.com/resources/compatibility/search.php?deviceCategory=software&testConfig=16).
 
 ### Docker images
-* Latest (Release v3.0):
+* Latest (Release v3.1):
   * projects.registry.vmware.com/gos_cert/ansible-vsphere-gos-validation:latest
-* Release v3.0:
-  * projects.registry.vmware.com/gos_cert/ansible-vsphere-gos-validation:v3.0
+* Release v3.1:
+  * projects.registry.vmware.com/gos_cert/ansible-vsphere-gos-validation:v3.1
 
 Launch testing using Docker image
 1. Execute below commands in your machine