Clarify MG custom profile props behaviour for search

Make it clear that custom profile properties must be set in at least the geo in which a profile is mastered in order to be displayed in people search results.

Author: jordanspooner

docs/solution-guidance/multigeo-userprofileexperience.md

@@ -128,6 +128,9 @@ You can add company-specific user profile properties to user profiles in SharePo
 - Custom user profile properties are created at the geo ___location level. If you create a property in the Europe geo ___location, that property is not available in the other geo locations. As a best practice, create custom user profile properties in all geo locations. This reduces the risk that data will be lost when a user moves across geo locations.
 - You must read and update custom user profile properties at the geo ___location level. If you created a custom property in all geo locations, you need to iterate over the geo locations and update the property for all  users.
 
+> [!NOTE]
+> For a custom profile property to show up for a user in people search results, the property must be created and set in at least the user's profile ___location. E.g., for a user with a profile located in NAM, the custom property must be set in at least the NAM geo in order to show up in people search results; for a user with a profile located in EUR, the custom property would have to be set in at least EUR.
+
 ```csharp
 // For SharePoint Online custom properties, use the following approach.
 string userPrincipalName = "[email protected]";