added dgss migration fixes

Author: TacoTechSharma

articles/trusted-signing/TOC.yml

@@ -25,7 +25,7 @@
     - name: Change Pricing Tier
       href: how-to-change-sku.md
     - name: Device Guard Signing Service Migration 
-      href: how-to-device-guard-signing-service-migration
+      href: how-to-device-guard-signing-service-migration.md
   - name: Tutorials
     items:
     - name: Assign roles in Trusted Signing