Update map.md

Author: DeveloperTryingToCodeLikeOtherOfThem

docs/map.md

@@ -1,3 +1,7 @@
 ## Map
 A map is similar to an array, but uses an object, or dictionary/map to store items  of different data types, like numbers and strings.
 Objects use key-value pairs, allowing values of any time, which provides the flexibility needed for data.
+Additionally, the key must be either a number or string, while the value type can be any type.
+``` ts
+    const myMap = {[index: string]: number}
+```