Update Map usage explanation in article.md #3903

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Expand Up		@@ -41,12 +41,25 @@ alert( map.size ); // 3

		As we can see, unlike objects, keys are not converted to strings. Any type of key is possible.

	```smart header="`map[key]` isn't the right way to use a `Map`"
	Although `map[key]` also works, e.g. we can set `map[key] = 2`, this is treating `map` as a plain JavaScript object, so it implies all corresponding limitations (only string/symbol keys and so on).
	````smart header="`map[key]` isn’t the correct way to use a `Map`"
	Although you can technically write `map[key] = value`, this does not store the data inside the `Map` collection.

	So we should use `map` methods: `set`, `get` and so on.
	Instead, it simply adds a regular property to the `Map` object itself—just like with plain JavaScript objects—and the key is always converted to a string.

	For example:

	```js run
	let map = new Map();
	map["1"] = "test"; // adds a property, not a Map entry

	alert(map.get("1")); // undefined
	alert(map["1"]); // "test"
		```

	To properly store and retrieve data in a `Map`, always use its methods:
	`map.set(key, value)` and `map.get(key)`.
	````

		Map can also use objects as keys.

		For instance:
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