Restored dash from group names

cassandra-maintenance.yml

diff --git a/cassandra-maintenance.yml b/cassandra-maintenance.yml
index 5c19392..63ed278 100644
--- a/cassandra-maintenance.yml
+++ b/cassandra-maintenance.yml
@@ -4,4 +4,4 @@
   serial: 1
   roles:
   - { role: apigee-opdk-cassandra-repair }
-  - { role: apigee-opdk-cassandra-rebuild, opdk_region: 'dc1' }
+  - { role: apigee-opdk-cassandra-rebuild, opdk_region: 'dc-1' }