add AI notice

Author: shanet

app/views/shared/_about.html.erb

@@ -23,6 +23,8 @@
 
 <%= render 'shared/copyright' %>
 
+<i class="fa-solid fa-robot me-1"></i><strong>AI notice:</strong> All content on Pirep is written and edited by humans. No AI is used to collect or populate airport descriptions, photos, or information.
+
 <hr>
 
 <p>