LMS: adding in supplemental 'volunteer to be a translator' action to language modal

lms/static/sass/shared/_modal.scss

@@ -342,5 +342,20 @@
   .list-input {
     margin-bottom: $baseline;
   }
+
+  .actions-supplemental {
+    padding: 0 ($baseline*2) $baseline ($baseline*2);
+
+    .list-actions-item {
+      @extend %t-copy-sub1;
+      color: $base-font-color;
+      text-align: center;
+    }
+
+    .action {
+      display: block;
+      margin-top: ($baseline/4);
+    }
+  }
 }
 

lms/templates/modal/_modal-settings-language.html

@@ -50,6 +50,12 @@
           <input type="submit" id="submit-lang" value="${_('Save Language Settings')}" />
         </div>
       </form>
+
+      <ul class="list list-actions actions-supplemental">
+        <li class="list-actions-item">
+        ${_("Don't see your preferred language? {link_start}Volunteer to become a translator!{link_end}").format(link_start='<a class=" action action-volunteer" rel="external" href="https://github.com/edx/edx-platform/blob/master/docs/en_us/developers/source/i18n_translators_guide.rst">', link_end="</a>")}
+        </li>
+      </ul>
     </div>
   </div>
 </section>