Update Profile insights.md

Updating to instruct users how to Filter by External ID Type effectively. It's important to highlight that the specific external ID value must be entered in the search bar for the search to be successful. At present, if the value isn't provided, there's no error message displayed in the user interface; it only appears in the developer tools console, which can be confusing. By clarifying this in the documentation, I hope to streamline user experience by clearly indicating the requirement of this specific input.

Author: samkcrespo

src/unify/insights.md

@@ -18,7 +18,11 @@ From the Profiles Insights page, you can navigate to these tabs:
 
 Use the errors and violations tab to view and help you troubleshoot any errors or violations that have occurred in your space.
 
-You can filter results by ID type, time range, specific violations, and more.
+You can filter results by ID type, time range, specific violations, and more. 
+
+To filter by External ID type, entering an External ID value in the search bar is required.
+<img width="873" alt="image" src="https://github.com/segmentio/segment-docs/assets/100810716/1ab5671b-3c6e-4ce2-a261-18e95d0b4c33">
+
 
 ### Errors