Correctly reference UtcNow instead of Now

Doco is misleading indicating that when the timer does not use high res it returns DateTime.Now but looking at source code I can see that in fact it returns DateTime.UtcNow, so changed the documentation to reflect this small detail.

Author: rsempire

xml/System.Diagnostics/Stopwatch.xml

@@ -435,7 +435,7 @@
           <format type="text/markdown"><![CDATA[  
   
 ## Remarks  
- If the <xref:System.Diagnostics.Stopwatch> class uses a high-resolution performance counter, <xref:System.Diagnostics.Stopwatch.GetTimestamp%2A> returns the current value of that counter. If the <xref:System.Diagnostics.Stopwatch> class uses the system timer, <xref:System.Diagnostics.Stopwatch.GetTimestamp%2A> returns the current <xref:System.DateTime.Ticks%2A?displayProperty=nameWithType> property of the <xref:System.DateTime.Now%2A?displayProperty=nameWithType> instance.  
+ If the <xref:System.Diagnostics.Stopwatch> class uses a high-resolution performance counter, <xref:System.Diagnostics.Stopwatch.GetTimestamp%2A> returns the current value of that counter. If the <xref:System.Diagnostics.Stopwatch> class uses the system timer, <xref:System.Diagnostics.Stopwatch.GetTimestamp%2A> returns the current <xref:System.DateTime.Ticks%2A?displayProperty=nameWithType> property of the <xref:System.DateTime.UtcNow%2A?displayProperty=nameWithType> instance.