Add header for table

Author: xenolinux

modules/hosted-control-planes-monitoring-dashboard.adoc

@@ -48,6 +48,7 @@ To generate dashboards for each hosted cluster, the HyperShift Operator uses a t
 
 When a dashboard is generated, the following strings are replaced with values that correspond to a specific hosted cluster:
 
+[cols="2,2",options="header"]
 |===
 | Name | Description
 | [x-]`__NAME__` | The name of the hosted cluster