Added a reminder for CS431/631 students.

Author: Alex-Weatherhead

assignments.html

@@ -66,7 +66,9 @@ <h1>Assignments <br/><small>Data-Intensive Distributed Computing (Winter 2019)</
   </div>
 
 <p>Note that there separate sets of assignments for CS 451/651 and CS
-431/631. Make sure you work on the correct asssignments!</p>
+431/631. <b>Students in CS431/631 must complete the set of assignments they
+  chose in the GitHub Sign-Up form</b>. Make sure you work on the correct asssignments!</p>
+     
 
 <p><a href="assignments-451.html" class="btn btn-success btn-large">CS 451/651 Assignments</a>
 <a href="assignments-431.html" class="btn btn-info btn-large">CS 431/631 Assignments</a></p>