Title text in allowHTML should work?

When pasting this configuration into https://export.highcharts.com/ we should get a proper result (and if not, there should be a clear note in the docs):

```JSON
{
"xAxis": {
"categories": [
"Jan",
"Feb",
"Mar",
"Apr",
"May",
"Jun",
"Jul",
"Aug",
"Sep",
"Oct",
"Nov",
"Dec"
]
},
"title": {
"text": "My custom title",
"useHTML": true
},
"series": [
{
"data": [
29.9,
71.5,
106.4,
129.2,
144,
176,
135.6,
148.5,
216.4,
194.1,
95.6,
54.4
]
}
]
}
```