Merge branch 'donate/flattr'

wiki/src/contribute/how/donate.mdwn

@@ -27,6 +27,8 @@ Ways to donate
 
   * [[Bitcoin|donate#bitcoin]]
 
+  * [Flattr us](https://flattr.com/submit/auto?user_id=tails_live&url=https://tails.boum.org&title=Tails)
+
   * If none of these methods suit you, consider [donating
     to the Tor Project](https://www.torproject.org/donate/). They do
     great work, and also support us financially.