add Gentoo trademark notice

public/packages.html

@@ -149,7 +149,8 @@
                     Unless otherwise stated, content on this page is licensed under a ISC License.
                 </p>
                 <p>
-                    Linux is a registered trademark of Linus Torvalds.</p>
+                    Linux is a registered trademark of Linus Torvalds. Gentoo is a trademark of the Gentoo Foundation.
+                </p>
                 <p>
                     All other trademarks are the property of their respective owners.
                 </p>