Properly explain why Migrate() has a return value

Author: Toastbrot236

Refresh.Workers/MigrationJob.cs

@@ -56,7 +56,8 @@ public override void ExecuteJob(WorkContext context)
     /// <returns>
     /// The number of entities in the batch, minus the number of entities removed from DB during this migration.
     /// E.g. if 1000 items are in the given batch, and 5 got removed from DB during migration, 
-    /// the returned number will be 1000 - 5 = 995
+    /// the returned number will be 1000 - 5 = 995.
+    /// This allows you to write migration jobs, which need to delete entities from the given batch, without breaking pagination done by the worker.
     /// </returns>
     protected abstract int Migrate(WorkContext context, TEntity[] batch);
 }