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/deepClone.md

@@ -4,7 +4,7 @@ Creates a deep clone of an object.
 
 Use recursion.
 Use `Object.assign()` and an empty object (`{}`) to create a shallow clone of the original.
-Use `Object.keys()` and `Array.forEach()` to determine which key-value pairs need to be deep cloned.
+Use `Object.keys()` and `Array.prototype.forEach()` to determine which key-value pairs need to be deep cloned.
 
 ```js
 const deepClone = obj => {