OCPBUGS-41139:adding new Azure region

Author: brendan-daly-red-hat

modules/installation-azure-regions.adoc

@@ -45,6 +45,7 @@ The installation program dynamically generates the list of available Microsoft A
 * `southcentralus` (South Central US)
 * `southeastasia` (Southeast Asia)
 * `southindia` (South India)
+* `spaincentral` (Spain Central)
 * `swedencentral` (Sweden Central)
 * `switzerlandnorth` (Switzerland North)
 //* uaecentral (UAE Central)