fix capitalization of windows update in TOC

Author: amsliu

support/azure/virtual-machines/windows/toc.yml

@@ -226,7 +226,7 @@
     href: in-place-system-upgrade.md
   - name: Upgrade VM to contain more than 64 vCPUs
     href: vm-cannot-upgrade-64-vcpu.md
-  - name: Windows update errors that require in-place upgrades
+  - name: Windows Update errors that require in-place upgrades
     href: windows-update-errors-requiring-in-place-upgrade.md
   - name: Known errors and issues
     items: