add popover docs

Co-authored-by: Florian Verdonck <[email protected]>

Author: dkirchhof

runtime/JsxDOM.res

@@ -24,7 +24,10 @@
 
 type style = JsxDOMStyle.t
 type domRef
-type popover = | @as("auto") Auto | @as("manual") Manual
+/**
+  [Read more on MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Global_attributes/popover)
+*/
+type popover = | @as("auto") Auto | @as("manual") Manual | @as("hint") Hint
 /**
   [Read more on MDN](https://developer.mozilla.org/en-US/docs/Web/HTML/Element/button#popovertargetaction)
 */