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/sortCharactersInString.md

@@ -2,7 +2,7 @@
 
 Alphabetically sorts the characters in a string.
 
-Use the spread operator (`...`), `Array.sort()` and  `String.localeCompare()` to sort the characters in `str`, recombine using `String.join('')`.
+Use the spread operator (`...`), `Array.prototype.sort()` and  `String.localeCompare()` to sort the characters in `str`, recombine using `String.prototype.join('')`.
 
 ```js
 const sortCharactersInString = str => [...str].sort((a, b) => a.localeCompare(b)).join('');