fix: update link for upgrade guide in documentation

Author: pascalinthecloud

docs/src/content/docs/index.mdx

@@ -8,7 +8,7 @@ hero:
     file: ../../assets/houston.webp
   actions:
     - text: Docs
-      link: /guides/upgrade_talos
+      link: /terraform-proxmox-talos-cluster/guides/upgrade_talos
       icon: right-arrow
     - text: Github
       link: https://github.com/pascalinthecloud/terraform-proxmox-talos-cluster