Correct unobserved Task exception behavior doc

The doc described .NET 4.0 behavior only without stating how on .NET 4.5+ the behavior changed.

Author: AArnott

xml/System.Threading.Tasks/Task.xml

@@ -2599,7 +2599,7 @@ Task t Status: RanToCompletion, Result: 42
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- Tasks that throw unhandled exceptions store the resulting exception and propagate it wrapped in a <xref:System.AggregateException> in calls to <xref:System.Threading.Tasks.Task.Wait%2A> or in accesses to the <xref:System.Threading.Tasks.Task.Exception%2A> property. Any exceptions not observed by the time the task instance is garbage collected will be propagated on the finalizer thread. For more information and an example, see [Exception Handling (Task Parallel Library)](~/docs/standard/parallel-programming/exception-handling-task-parallel-library.md).  
+ Tasks that throw unhandled exceptions store the resulting exception and propagate it wrapped in a <xref:System.AggregateException> in calls to <xref:System.Threading.Tasks.Task.Wait%2A> or in accesses to the <xref:System.Threading.Tasks.Task.Exception%2A> property. On .NET 4.0, any exceptions not observed by the time the task instance is garbage collected will be propagated on the finalizer thread, which crashes the process. On .NET 4.5 and later, unobserved exceptions are not rethrown from the Finalizer. For more information and an example, see [Exception Handling (Task Parallel Library)](~/docs/standard/parallel-programming/exception-handling-task-parallel-library.md).  
   
  ]]></format>
         </remarks>