feat: add screenshot of user dismissible checkbox

Author: imjohnbo

assets/images/enterprise/site-admin-settings/user-dismissible-checkbox.png

@@ -107,6 +107,8 @@ You can also set an announcement banner{% ifversion ghes %} in the administrativ
 
 You can also set an announcement banner in the administrative shell using a command line utility. For more information, see "[Command-line utilities](/enterprise/admin/configuration/command-line-utilities#ghe-announce)."
 
+{% endif %}
+
 {% data reusables.enterprise-accounts.access-enterprise %}
 {% data reusables.enterprise-accounts.settings-tab %}
 {% data reusables.enterprise-accounts.messages-tab %}
@@ -116,5 +118,9 @@ You can also set an announcement banner in the administrative shell using a comm
   ![Text field to enter announcement](/assets/images/enterprise/site-admin-settings/announcement-text-field.png)
 1. Optionally, under "Expires on", select the calendar drop-down menu and click an expiration date.
   ![Calendar drop-down menu to choose expiration date](/assets/images/enterprise/site-admin-settings/expiration-drop-down.png)
+{% ifversion ghe-announce-dismiss %}
+1. Optionally, enable the "User dismissible" checkbox to make the announcement dismissible by each user.
+  ![User dismissible checkbox](/assets/images/enterprise/site-admin-settings/user-dismissible-checkbox.png)
+{% endif %}
 {% data reusables.enterprise_site_admin_settings.message-preview-save %}
 {% endif %}