feat(documentdb): Update example yaml

Signed-off-by: P-Louw <[email protected]>

Author: P-Louw

charts/cluster/examples/documentdb.yaml

@@ -6,5 +6,7 @@ version:
   ferretdb: "2.5.0"
 cluster:
   instances: 1
+ferretdb:
+  enabled: true
 backups:
   enabled: false