Issue #2678550 by imrancluster: Need full stop (.) for description field's...

Issue #2678550 by imrancluster: Need full stop (.) for description field's help text in Add comment type' section

(cherry picked from commit 85ef01de)

core/modules/comment/src/CommentTypeForm.php

@@ -96,7 +96,7 @@ public function form(array $form, FormStateInterface $form_state) {
     $form['description'] = array(
       '#type' => 'textarea',
       '#default_value' => $comment_type->getDescription(),
-      '#description' => t('Describe this comment type. The text will be displayed on the <em>Comment types</em> administration overview page'),
+      '#description' => t('Describe this comment type. The text will be displayed on the <em>Comment types</em> administration overview page.'),
       '#title' => t('Description'),
     );