Document that you can do "intrinsic JSX elements"

Intrinsic JSX elements = lowercase JSX elements (<mesh /> from ThreeJs for example) that takes their own props, not just domProps which all lowercase JSX elements automatically do today.

This can be expressed already:

module Mesh = {
  type props = {
    position: (float, float, float),
    ref?: ReactDOM.domRef,
    scale?: float,
    onClick?: ReactEvent.Mouse.t => unit,
    onPointerOver?: ReactEvent.Mouse.t => unit,
    onPointerOut?: ReactEvent.Mouse.t => unit,
    children?: React.element,
  }

  @module("react/jsx-runtime") external make: (@as("mesh") _, props) => React.element = "jsx"
}

let rendered = <Mesh /> // will output <mesh> in the HTML

We need to document it.

No documentation file or test is named in the issue. Locate the relevant JSX documentation, use the supplied Mesh example as the basis for the explanation, and consider the work done when intrinsic JSX elements and their custom props are clearly documented.