correcting needed markup for cohort management static UX template

lms/templates/ux/reference/instructor_dashboard/membership.html

@@ -44,6 +44,8 @@
         <section class="instructor-dashboard-content-2" id="instructor-dashboard-content">
             <h1>Instructor Dashboard</h1>
 
+            <section class="idash-section active-section" id="membership">
+
                 <div class="batch-enrollment membership-section">
                     <h2> Batch Enrollment </h2>
                     <p>
@@ -366,4 +368,7 @@
                 <p class=""><i class="icon icon-info-sign"></i> You may view individual student information for each cohort via your entire course profile data download on <a href="" class="link-cross-reference">the data download view</a></p>
             </div>
         </div>
+    </section>
+    </section>
+    </div>
 </section>