remove unnecessary comment

Author: shxjames

challenges/hard/83_turboquant_attention/challenge.html

@@ -7,7 +7,7 @@
 </p>
 
 <p>
-  <strong>Background - how the keys were compressed</strong> (already done for you, not part of the challenge):
+  <strong>Background - how the keys were compressed</strong> (Not part of the challenge):
 </p>
 <ol>
   <li><strong>Rotate</strong>: multiply key by orthogonal matrix \(\Pi\): \(\;y = \Pi \cdot K\). This makes each