Fix post url

Author: vitorfs

django_school/classroom/templates/classroom/home.html

@@ -9,7 +9,7 @@ <h2>Welcome to the Django Schools! <span class="icon-emo-happy"></span></h2>
   <hr>
   <h3>What's this about?</h3>
   <p>
-    This Django application is an example I created to illustrate a <a href="https://simpleisbetterthancomplex.com/tutorial/2018/01/19/how-to-implement-multiple-user-types-with-django.html">blog post about how to implement multiple user types</a>.
+    This Django application is an example I created to illustrate a <a href="https://simpleisbetterthancomplex.com/tutorial/2018/01/18/how-to-implement-multiple-user-types-with-django.html">blog post about how to implement multiple user types</a>.
     In this application, users can sign up as a student or a teacher. Teachers can create quizzes and students can answer quizzes
     based on their interests.
   </p>

django_school/templates/base.html

@@ -61,7 +61,7 @@ <h1 class="logo">
           <footer>
             <a href="https://simpleisbetterthancomplex.com">© SimpleIsBetterThanComplex.com</a>
             /
-            <a href="https://simpleisbetterthancomplex.com/tutorial/2018/01/19/how-to-implement-multiple-user-types-with-django.html">Read more about this example</a>
+            <a href="https://simpleisbetterthancomplex.com/tutorial/2018/01/18/how-to-implement-multiple-user-types-with-django.html">Read more about this example</a>
             /
             <a href="https://github.com/sibtc/django-multiple-user-types-example">GitHub repository</a>
           </footer>