cmd/tailscale/cli: fix TUNmode display on synology web page
Fixes
</div>
{{ if .IsSynology }}
<div class="border border-gray-200 bg-orange-0 rounded-lg p-2 pl-3 pr-3 mb-8 width-full text-orange-800">
- Outgoing access {{ if true }}enabled{{ else }}not configured{{ end }}.
+ Outgoing access {{ if .TUNMode }}enabled{{ else }}not configured{{ end }}.
<nobr><a href="https://tailscale.com/kb/1152/synology-outbound/"
class="font-medium link"
target="_blank"
