Avoid confusing prototype methods for static methods

Correct: `Array.from()` (it’s a static method)
Incorrect: `Array.join()` (doesn’t exist; it’s a prototype method)

This patch uses the common `#` syntax to denote `.prototype.`.

snippets/initializeNDArray.md

@@ -3,7 +3,7 @@
 Create a n-dimensional array with given value.
 
 Use recursion.
-Use `Array.map()` to generate rows where each is a new array initialized using `initializeNDArray`.
+Use `Array.prototype.map()` to generate rows where each is a new array initialized using `initializeNDArray`.
 
 ```js
 const initializeNDArray = (val, ...args) =>