Mentioned that validator can validate DateTimeInterface too

Author: javiereguiluz

reference/constraints/Time.rst

@@ -1,9 +1,9 @@
 Time
 ====
 
-Validates that a value is a valid time, meaning either a ``DateTime`` object
-or a string (or an object that can be cast into a string) that follows
-a valid "HH:MM:SS" format.
+Validates that a value is a valid time, meaning an object implementing
+``DateTimeInterface`` or a string (or an object that can be cast into a string)
+that follows a valid ``HH:MM:SS`` format.
 
 +----------------+------------------------------------------------------------------------+
 | Applies to     | :ref:`property or method <validation-property-target>`                 |