Update xml/System.Diagnostics/Activity.xml

Co-authored-by: Genevieve Warren <24882762+gewarren@users.noreply.github.com>

Author: tarekgh

xml/System.Diagnostics/Activity.xml

@@ -1116,7 +1116,7 @@ The specified format will take precedence over `Parent.IdFormat`, the <xref:Syst
 ## Remarks
 
 - This method should only be used in 'boundary' scenarios where an <xref:System.Diagnostics.Activity> from another process logically started this <xref:System.Diagnostics.Activity>. The `parentId` brings up the <xref:System.Diagnostics.Activity.Tags> (as well as the <xref:System.Diagnostics.Activity.ParentId> property) and can be used to reconstruct the causal tree.
-- This method should only be used before starting the <xref:System.Diagnostics.Activity> object. Calling this method after the starting of the <xref:System.Diagnostics.Activity> object will have no effect.
+- This method should only be used before starting the <xref:System.Diagnostics.Activity> object. This method has no effect if you call it after the <xref:System.Diagnostics.Activity> object has started.
 
 ]]></format>
         </remarks>