update docs

docs/30_Usage.md

@@ -4,7 +4,8 @@
 
 To browse emails and view each message open <http://localhost/vendor/emailcatcher/viewer.php>
 
-You see a list of emails.
+If one or more emails are stored you get a view with a list of emails.
+On top are tiles with number of stored messages and the age of the last email followed by a filter field.
 
 ![Screenshot: List of emails](images/screenshot_list_emails.png)