Fix java21-quiz.html!

Author: Anass Rach

java21-quiz.html

@@ -318,6 +318,8 @@ <h2>Quiz Complete!</h2>
                 <div class="final-score" id="finalScore">0/10</div>
                 <div class="score-message" id="scoreMessage">Great job!</div>
                 <button class="btn btn-primary" onclick="restartQuiz()">Restart Quiz</button>
+				<button class="btn btn-primary" onclick="window.location.href='/java21docCards/'">
+					Study Flashcards </button>
             </div>
         </div>
     </div>