MDL-61033 mod_quiz: Update lang string

mod/quiz/lang/en/quiz.php

@@ -91,7 +91,7 @@
 $string['attemptedon'] = 'Attempted on';
 $string['attempterror'] = 'You are not allowed to attempt this quiz at this time because: {$a}';
 $string['attempterrorinvalid'] = 'Invalid quiz attempt ID';
-$string['attempterrorcontentchange'] = 'This quiz attempt no longer exists. (When a quiz is edited in-progress previews are automatically deleted.)';
+$string['attempterrorcontentchange'] = 'This quiz preview no longer exists. (When a quiz is edited, any in-progress previews are automatically deleted.)';
 $string['attempterrorcontentchangeforuser'] = 'This quiz attempt no longer exists.';
 $string['attemptfirst'] = 'First attempt';
 $string['attemptincomplete'] = 'That attempt (by {$a}) is not yet completed.';