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/initialize2DArray.md

@@ -2,7 +2,7 @@
 
 Initializes a 2D array of given width and height and value.
 
-Use `Array.map()` to generate h rows where each is a new array of size w initialize with value. If the value is not provided, default to `null`.
+Use `Array.prototype.map()` to generate h rows where each is a new array of size w initialize with value. If the value is not provided, default to `null`.
 
 ```js
 const initialize2DArray = (w, h, val = null) =>