Fix doubke the

Author: przemyslaw-bogusz

reference/constraints/AtLeastOneOf.rst

@@ -186,7 +186,7 @@ messageCollection
 
 **type**: ``string`` **default**: ``Each element of this collection should satisfy its own set of constraints.``
 
-This is the the message that will be shown if the validation fails
+This is the message that will be shown if the validation fails
 and the internal constraint is either :doc:`/reference/constraints/All`
 or :doc:`/reference/constraints/Collection`. See option `message`_ for an example.