fix: testimonial, closes #181

Author: Helias

testimonials.html

@@ -11,7 +11,7 @@
         </div>
         <div class="row">
             <div class="col-md-12">
-                <center>Read <a href="/testimonials-how-to">this guide</a> to add your post in this page (alphabetically order)</center>
+                <center>Read <a href="https://github.com/azerothcore/azerothcore.github.io/blob/master/testimonials-how-to.md">this guide</a> to add your post in this page (alphabetically order)</center>
             </div>
         </div>