Update toc.yml

Author: ikhapova

articles/advisor/toc.yml

@@ -70,6 +70,8 @@
     href: advisor-azure-resource-graph.md
   - name: Consume Advisor score 
     href: azure-advisor-score.md
+  - name: Calculate cost savings
+    href: advisor-how-to-calculate-total-cost-savings.md
 - name: Reference
   items:
   - name: Security baseline