UMLR — Clarify that deep history uses the same default transition strategy as shallow history

Issue: In section 14.2.3.7, it is stated explicitly that, for the shallowHistory pseudostate:

"A single outgoing Transition from this Pseudostate may be defined terminating on a substate of the composite
State. This substate is the default shallow history state of the composite State."

However, there is no corresponding text for the deepHistory pseudostate. There does not seem to be any reason why the latter should not use the same strategy for a default deep history.

Proposed solution: Insert the following text in the paragraph describing deepHistory pseudostate semantics:

"A single outgoing Transition from this Pseudostate may be defined terminating on a substate of the composite
State. This substate is the default deep history state of the composite State."