Add documentation on Universal date format (#249)

* Add documentation on Universal date format

This PR seeks to add a section for the newest date format (Universal) 
  to the Files docs, which currently only mention Application & System.

The new header and brief description complement the style of the existing 
  format options.

Source Path: [`Website/src/routes/docs/configuring/date-formats.md`](https://github.com/files-community/Website/blob/main/src/routes/docs/configuring/date-formats.md)
Public URL: [Files Documentation](https://files.community/docs/configuring/date-formats)

* Edit: adjusts Universal example date to match rest

Signed-off-by: Michael Rehnert <dmreh@outlook.com>

src/routes/docs/configuring/date-formats.md

@@ -1,11 +1,15 @@
 # Date Formats
 
-Files comes with two different options to let you customize the date format.
+Files comes with three different options to let you customize the date format.
 
 **Application**
 
 The default date format uses the following format _Wednesday, June 3, 2020_.
 
 **System**
 
-System is a little more compact and uses this format _6/3/2020_.
+System is a little more compact and uses this format _6/3/2020_.
+
+**Universal**
+
+Universal uses the defacto official international format _2020-06-03_.