Reword JavaScript fallback notice to explain trigger without assuming cause (#2861)

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
Co-authored-by: Jacob Coffee <jacob@z7x.org>

Author: 3 people

templates/base.html

@@ -129,7 +129,7 @@
     <div id="touchnav-wrapper">
 
         <div id="nojs" class="do-not-print">
-            <p><strong>Notice:</strong> While JavaScript is not essential for this website, your interaction with the content will be limited. Please turn JavaScript on for the full experience. </p>
+            <p><strong>Notice:</strong> This page displays a fallback because interactive scripts did not run. Possible causes include disabled JavaScript or failure to load scripts or stylesheets.</p>
         </div>
 
         <!-- Sister Site Links -->