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/castArray.md

@@ -2,7 +2,7 @@
 
 Casts the provided value as an array if it's not one.
 
-Use `Array.isArray()` to determine if `val` is an array and return it as-is or encapsulated in an array accordingly.
+Use `Array.prototype.isArray()` to determine if `val` is an array and return it as-is or encapsulated in an array accordingly.
 
 ```js
 const castArray = val => (Array.isArray(val) ? val : [val]);