Add changelog for users stats feature

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

app/views/admin/dashboard/index.html.haml

@@ -23,6 +23,7 @@
               %h3.text-center
                 Users:
                 = number_with_delimiter(User.count)
+            - # EE specific
             .text-center
               = link_to 'Users statistics', admin_dashboard_stats_path
             %hr

changelogs/unreleased-ee/4920-count-of-users-by-role-in-admin.yml

+---
+title: Add users stats page for admin area with per role amount
+merge_request: 4539
+author:
+type: changed