Update storage-files-redundancy-premium-zrs.md

adding Korea Central to list of regions supported by ZRS Premium Files

Author: gayatrikishore

includes/storage-files-redundancy-premium-zrs.md

@@ -11,6 +11,7 @@ ZRS for premium file shares is available for a subset of Azure regions:
 - (Asia Pacific) Australia East
 - (Asia Pacific) Japan East
 - (Asia Pacific) Southeast Asia
+- (Asia Pacific) Korea Central
 - (Europe) France Central
 - (Europe) North Europe
 - (Europe) West Europe