Update acknowledgement.html

acknowledgement.html

@@ -29,7 +29,7 @@
       <div class="container">
         <div class="row">
           <div class="col-lg-8 col-lg-offset-2 centered">
-            <h2>We would like to thank our sponsors for their generous contribution, without whom this event would not have been possible.</h2>
+            <h2>We would like to thank our previous sponsors for their generous contribution, without whom this event would not have been possible.</h2>
             <br>
             <img class="img-responsive center-block" style="width:800px;max-width:100%" src="assets/img/sponsor_230414.png" alt="Previous NoCaSS sponsors">
             <br>