Note TAG guidance on private browsing modes in mitigations (#224)

Credits to Ehsan Toreini for his related research and suggestions

index.html

@@ -1171,6 +1171,9 @@ <h3>Mitigation strategies</h3>
     <div class="note">
       This section gives a high-level view into mitigation strategies applicable to this specification.
       The normative definitions of these mitigations are integrated into the respective algorithms of this specification.
+      Implementers are advised to consider the
+      <a href="https://www.w3.org/2001/tag/doc/private-browsing-modes/#features-supporting-private-browsing">TAG guidance
+      on private browsing modes</a> when implementing the mitigations defined in this specification.
     </div>
 
     <h4>Data minimization</h4>
@@ -1446,7 +1449,8 @@ <h2>
   <p>
     Thanks to the W3C Privacy Interest Group (PING) and especially Peter Snyder
     for the privacy review, feedback and the proposed cross-site covert channel
-    attack and its mitigations.
+    attack and its mitigations. Similarly thanks to Ehsan Toreini for his work on
+    the privacy of private browsing and related contributions to this specification.
   </p>
   <p>
     Special thanks to