[DOC-11486]: Raise visibility of 'Guarding against Data Loss during XDCR' section (#3693)

Added a warning and a link to the xdcr-overview.adoc page.

Author: RayOffiah

modules/learn/pages/clusters-and-availability/xdcr-overview.adoc

@@ -129,6 +129,13 @@ The data in any source collection can be replicated to any target collection, as
 
 * _Migration_.
 Data in the _default_ collection of a source bucket can be replicated to an administrator-defined collection in the target bucket.
++
+[WARNING]
+====
+Be aware that performing data migration may result in data loss when using XDCR filters to delete data.
+
+If you are running filters that remove data, be sure to read xref:clusters-and-availability/xdcr-filtering.adoc#configuring-deletion-filters-to-prevent-data-loss[Configuring Deletion Filters to Prevent Data-Loss] before attempting a migration.
+====
 
 In each case, _filtering_ can be applied.