Avoid negation

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

@@ -3,7 +3,7 @@
 In rare occasions, you might have to perform a file system check to repair a
 broken persistent volume.
 
-1. Start Tails, without persistence enabled, and [[set up an administration
+1. Start Tails, with persistence disabled, and [[set up an administration
    password|startup_options/administration_password]].
 
 1. Choose