Call-out issues - Formatting issue in NGF upgrade doc

[sjberman]

Describe the bug

There appears to be a formatting issue in this section of the NGF upgrade doc with the NGINX Plus callout.

[JTorreG]

I have found a workaround adding a title to the callout
#1196

But I think Callouts that have a heading row, without title, inside of tabs are failing to render properly

cc @nginx-jack