Fix live-additional-software.conf path

wiki/src/doc/first_steps/persistence/configure.mdwn

@@ -292,7 +292,7 @@ connect Tails to Internet with persistence activated.
 </div>
 
 To choose the list of additional software, create a file called
-`/lib/live/mount/persistence/XXX_unlocked/live-additional-software.conf`
+`/live/persistence/XXX_unlocked/live-additional-software.conf`
 (`XXX` corresponds to the name of the device where the persistent
 storage is stored: probably `sdb2`). Each line of this file must contain
 the name of a Debian package to be installed as an additional software