Fix midterm 2 timeline.

Author: dvanhorn

www/midterms/2.scrbl

@@ -9,7 +9,7 @@
 
 @bold{Due: @m2-date 3:15PM}
 
-Midterm 2 will be released at least 72 hours prior to its due date.
+Midterm 2 will be released at least 48 hours prior to its due date.
 
 @section{Instructions}