JSX tag-class (HTML Element vs Component Element)

[Templarian]

In JSX it's a subtle feature, but editors [Ex: VS Code] syntax highlight the difference between native HTML elements (Ex: <a>, <span>) and component classes (Ex: <DropDown>, <Foo>).

Basically, if it does not have a capital [^a-z] for the first character it would be helpful to have another class name appended. Like tag-class or something.

<foo  = <span class="token tag"><span class="token punctuation">&lt;</span>foo</span>

<Foo  = <span class="token tag tag-class"><span class="token punctuation">&lt;</span>Foo</span>
                               ^ Goal: Add this class name

I was looking below, but I can't get my head around how to achieve this for a PR (so I made this issue).

https://github.com/PrismJS/prism/blob/master/components/prism-jsx.js

Very low priority, but trying to make custom components in ReactJS documentation stand out more.