mention subdivision confidence limitations in csv

Author: NajiObeid

layouts/shortcodes/csv-block-table.html

@@ -345,8 +345,10 @@
             <td>subdivision_confidence</td>
             <td>decimal (1-100)</td>
             <td>
-              The confidence that the most specific subdivision was correctly
-              geolocated.
+              The confidence that the most specific subdivision was correctly geolocated.
+              <br/>
+              <br/>
+              Confidence levels for both the first and second subdivisions are exclusively available in the MMDB files.
               <br/>
               <br/>
               <a