Update manage-cost-storage.md

Added link to purge doc,
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cc: @bwren

Author: DaleKoetke

articles/azure-monitor/logs/manage-cost-storage.md

@@ -197,7 +197,7 @@ By default, two data types - `Usage` and `AzureActivity` - are retained for a mi
 
 Data types from workspace-based Application Insights resources (`AppAvailabilityResults`, `AppBrowserTimings`, `AppDependencies`, `AppExceptions`, `AppEvents`, `AppMetrics`, `AppPageViews`, `AppPerformanceCounters`, `AppRequests`, `AppSystemEvents`, and `AppTraces`) are also retained for 90 days at no charge by default. Their retention can be adjusted using the retention by data type functionality. 
 
-The Log Analytics [purge API](/rest/api/loganalytics/workspacepurge/purge) doesn't affect retention billing and is intended to be used for very limited cases. To reduce your retention bill, the retention period must be reduced either for the workspace or for specific data types. 
+The Log Analytics [purge API](/rest/api/loganalytics/workspacepurge/purge) doesn't affect retention billing and is intended to be used for very limited cases. To reduce your retention bill, the retention period must be reduced either for the workspace or for specific data types. Learn more about managing [personal data stored in Log Analytics and Application Insights](./personal-data-mgmt.md).
 
 ### Retention by data type