Correcting valueCount mapping

valueCount field in classic components is ItemCount in Workspace components. See https://learn.microsoft.com/en-us/azure/azure-monitor/reference/tables/appmetrics. Need to fix the reference here.

Author: toddfoust

articles/azure-monitor/app/convert-classic-resource.md

@@ -566,7 +566,7 @@ Legacy table: customMetrics
 |user_AuthenticatedId|string|UserAuthenticatedId|string|
 |user_Id|string|UserId|string|
 |value|real|(removed)||
-|valueCount|int|ValueCount|int|
+|valueCount|int|ItemCount|int|
 |valueMax|real|ValueMax|real|
 |valueMin|real|ValueMin|real|
 |valueSum|real|ValueSum|real|