README: Unlink role names which don't resolve in the galaxy UI

Author: markgoddard

README.md

@@ -6,13 +6,13 @@ This collection includes content for interacting with OpenStack clouds.
 
 ### Roles
 
-- [os_container_clusters](roles/os_container_clusters)
-- [os_deploy_templates](roles/os_deploy_templates)
-- [os_flavors](roles/os_flavors)
-- [os_host_aggregates](roles/os_host_aggregates)
-- [os_images](roles/os_images)
-- [os_networks](roles/os_networks)
-- [os_openstackclient](roles/os_openstackclient)
-- [os_openstacksdk](roles/os_openstacksdk)
-- [os_projects](roles/os_projects)
-- [os_volumes](roles/os_volumes)
+- os_container_clusters
+- os_deploy_templates
+- os_flavors
+- os_host_aggregates
+- os_images
+- os_networks
+- os_openstackclient
+- os_openstacksdk
+- os_projects
+- os_volumes