adding a section about firefox private mode clipboard

wiki/src/support/faq.mdwn

@@ -266,6 +266,17 @@ portals|doc/anonymous_internet/unsafe_browser]]. It is not meant to be used as a
 regular web browser. As a consequence, the files that you might download using
 the Unsafe Browser are not accessible by your user.
 
+<a id="browser_clipboard"></a>
+
+Can I share the same clipboard over separate browsing sessions?
+---------------------------------------------------------------
+
+No. As the Tor browser shipped in Tails is based on the private browsing mode of
+Firefox, every time you end it, by exiting Tor browser, the browsing
+[clipboard is cleared](https://developer.mozilla.org/en-US/docs/Using_the_Clipboard).
+If you need to copy something from your browsing session (e.g. a link)
+to use it later on, you should rather store it elsewhere (e.g. in gedit).
+
 <a id="persistence"></a>
 
 Persistence