Add WeakMap resources (#1637)

content/roadmaps/106-javascript/content/104-javascript-data-structures/101-keyed-collections/101-weak-map.md

@@ -1 +1,7 @@
-# Weak map
+# Weak map
+
+[WeakMap](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap) is a Map-like collection of key/value pairs whose keys must be objects, it removes them once they become inaccessible by other means
+
+<ResourceGroupTitle>Free Content</ResourceGroupTitle>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/WeakMap'>WeakMap</BadgeLink>
+<BadgeLink colorScheme='yellow' badgeText='Read' href='https://javascript.info/weakmap-weakset'>WeakMap and WeakSet</BadgeLink>