fixed build error

Author: KumudD

articles/virtual-network/toc.yml

@@ -278,7 +278,7 @@
         - name: Setup DPDK
           href: setup-dpdk.md
     - name: TCP/IP Performance Tuning for Azure VMs
-    href: virtual-network-tcpip-performance-tuning.md    
+      href: virtual-network-tcpip-performance-tuning.md    
     - name: Virtual machine network throughput
       href: virtual-machine-network-throughput.md
   - name: Move across regions