Fix Translator comment syntax in Mako templates [TNL-3277]

lms/templates/courseware/course_about.html

@@ -242,8 +242,8 @@ from edxmako.shortcuts import marketing_link
                 site_domain = microsite.get_value('site_domain', settings.SITE_NAME)
                 platform_name = microsite.get_value('platform_name', settings.PLATFORM_NAME)
 
-                # Translators: This text will be automatically posted to the student's
-                # Twitter account. {url} should appear at the end of the text.
+                ## Translators: This text will be automatically posted to the student's
+                ## Twitter account. {url} should appear at the end of the text.
                 tweet_text = _("I just registered for {number} {title} through {account}: {url}").format(
                     number=course.number,
                     title=get_course_about_section(course, 'title'),

lms/templates/courseware/progress.html

@@ -75,7 +75,7 @@ from django.utils.http import urlquote_plus
               </div>
               %elif is_generating:
               <div class="msg-content">
-                # Translators: This message appears to users when the system is processessing course certificates, which can take a few hours.
+                ## Translators: This message appears to users when the system is processessing course certificates, which can take a few hours.
                 <h2 class="title">${_("We're working on it...")}</h2>
                 <p class="copy">${_("We're creating your certificate. You can keep working in your courses and a link to it will appear here and on your Dashboard when it is ready.")}</p>
               </div>

lms/templates/shoppingcart/shopping_cart.html

@@ -15,7 +15,7 @@ from django.utils.translation import ungettext
 
   % if is_course_enrollment_closed:
     <%
-      # Translators: course_names is a comma-separated list of one or more course names
+      ## Translators: course_names is a comma-separated list of one or more course names
       expiry_message = ungettext(
           "{course_names} has been removed because the enrollment period has closed.",
           "{course_names} have been removed because the enrollment period has closed.",