Update TOC casing for virtual network routing appliance

Author: asudbring

articles/virtual-network/toc.yml

@@ -20,7 +20,7 @@
       href: /azure/well-architected/service-guides/virtual-network
     - name: What is network foundations?
       href: /azure/networking/foundations/network-foundations-overview
-    - name: Virtual Network routing appliance
+    - name: Virtual network routing appliance
       href: virtual-network-routing-appliance-overview.md
 - name: Get started
   items:
@@ -34,7 +34,7 @@
       href: virtual-network-vnet-plan-design-arm.md
     - name: Traffic routing
       href: virtual-networks-udr-overview.md
-    - name: Create a Virtual Network routing appliance
+    - name: Create a virtual network routing appliance
       href: how-to-create-virtual-network-routing-appliance.md
 - name: Security
   items: