Merge pull request #7382 from tarekgh/ActivitySetParentRemarks

Author: tarekgh

xml/System.Diagnostics/Activity.xml

@@ -1115,7 +1115,8 @@ The specified format will take precedence over `Parent.IdFormat`, the <xref:Syst
 
 ## Remarks
 
-This property 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 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. This method has no effect if you call it after the <xref:System.Diagnostics.Activity> object has started.
 
 ]]></format>
         </remarks>
@@ -1155,7 +1156,8 @@ This property should only be used in 'boundary' scenarios where an <xref:System.
 
 ## Remarks
 
-This method has the advantage that no string manipulation is needed to set the ID.
+- This method has the advantage that no string manipulation is needed to set the ID.
+- 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>