WeakSet docstrings (#7986)

* WeakSet docstrings

* More examples and MDN links

Author: fhammerschmidt

packages/@rescript/runtime/Stdlib_WeakSet.res

@@ -1,10 +1,75 @@
+/***
+Bindings to JavaScript's `WeakSet`.
+
+Weak sets store references to objects without preventing those objects from being garbage collected.
+*/
+
+/** Mutable weak set storing object references of type `'a`. */
 @notUndefined
 type t<'a>
 
+/**
+Creates an empty weak set.
+
+See [`WeakSet`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet) on MDN.
+
+## Examples
+
+```rescript
+let visited = WeakSet.make()
+WeakSet.has(visited, Object.make()) == false
+```
+*/
 @new external make: unit => t<'a> = "WeakSet"
 
+/**
+`add(set, value)` inserts `value` into the weak set and returns the set for chaining.
+
+See [`WeakSet.prototype.add`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet/add) on MDN.
+
+## Examples
+
+```rescript
+let set = WeakSet.make()
+let node = Object.make()
+WeakSet.add(set, node)
+WeakSet.has(set, node) == true
+```
+*/
 @send external add: (t<'a>, 'a) => t<'a> = "add"
+
+/**
+`delete(set, value)` removes `value` and returns `true` if an entry existed.
+
+See [`WeakSet.prototype.delete`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet/delete) on MDN.
+
+## Examples
+
+```rescript
+let set = WeakSet.make()
+let node = Object.make()
+let _ = WeakSet.add(set, node)
+WeakSet.delete(set, node) == true
+WeakSet.delete(set, node) == false
+```
+*/
 @send external delete: (t<'a>, 'a) => bool = "delete"
+
+/**
+`has(set, value)` checks whether `value` exists in the weak set.
+
+See [`WeakSet.prototype.has`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakSet/has) on MDN.
+
+## Examples
+
+```rescript
+let set = WeakSet.make()
+let node = Object.make()
+WeakSet.has(set, node) == false
+let _ = WeakSet.add(set, node)
+WeakSet.has(set, node) == true
+```
+*/
 @send external has: (t<'a>, 'a) => bool = "has"
 
 /**