tweak toc

Author: vhorne

articles/firewall/toc.yml

@@ -131,7 +131,7 @@ items:
       href: firewall-multi-hub-spoke.md
     - name: Azure Firewall with Microsoft Sentinel
       href: firewall-sentinel-overview.md
-    - name: Best practices for Performance
+    - name: Best practices for performance
       href: firewall-best-practices.md
 - name: How-to guides
   items: