Update cdn-custom-ssl.md

Correcting an issue flagged by the loc team per https://mseng.visualstudio.com/TechnicalContent/_workitems/edit/1597372

Author: Craig Casey

articles/cdn/cdn-custom-ssl.md

@@ -127,7 +127,7 @@ Grant Azure CDN permission to access the certificates (secrets) in your Azure Ke
 
     ![Access policy settings](./media/cdn-custom-ssl/cdn-access-policy-settings.png)
 
-3. Select **Get Secret permissions** and then get and list **Certificate permissions** to allow CDN to perform these permissions to get and list the certificates. 
+3. Select **Certificate permissions**, and then select the check boxes for **Get** and **List** to allow CDN to perform these permissions to get and list the certificates.
 
 4. Select **OK**.