Fix open tracking description

Author: norico0124

source/User_Guide/Settings/tracking.md

@@ -51,7 +51,7 @@ Open Tracking
 {% endanchor %}
 
 {% info %}
-If you are using domain whitelabeling, then your open tracking image will be served from your whitelabel domain instead of from SendGrid.net.
+If you are using email link whitelabeling, then your open tracking image will be served from your whitelabel domain instead of from SendGrid.net.
 {% endinfo %}
 
 Open Tracking adds an invisible image at the end of the email which can track email [opens]({{root_url}}/Glossary/opens.html). If the email recipient has images enabled on their email client, a request to SendGrid’s server for the invisible image is executed and an open event is logged. These events are logged in the  Statistics portal, Email Activity interface, and are reported by the Event Webhook.