Fix link to the s/Torbutton/Tor Browser/ design doc.

wiki/src/doc/anonymous_internet/Tor_Browser.mdwn

@@ -108,8 +108,8 @@ We consider this as a necessary compromise between security and usability and as
 of today we are not aware of any JavaScript that would compromise Tails
 anonymity.
 
-For more technical details you can refer to the [Torbutton design
-document](https://www.torproject.org/torbutton/en/design/).
+For more technical details you can refer to the [Tor Browser design
+document](https://www.torproject.org/projects/torbrowser/design/).
 
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