Update toc.yml

Author: cynthn

articles/virtual-machines/linux/toc.yml

@@ -177,6 +177,7 @@
         href: reserved-vm-instance-size-flexibility.md
     - name: Spot VMs
       href: spot-vms.md
+      displayName: pre-empt, preempt
     - name: Previous generations
       href: ../sizes-previous-gen.md?toc=/azure/virtual-machines/linux/toc.json&bc=/azure/virtual-machines/linux/breadcrumb/toc.json
     - name: Isolated sizes