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/similarity.md

@@ -2,7 +2,7 @@
 
 Returns an array of elements that appear in both arrays.
 
-Use `Array.filter()` to remove values that are not part of `values`, determined using `Array.includes()`.
+Use `Array.prototype.filter()` to remove values that are not part of `values`, determined using `Array.prototype.includes()`.
 
 ```js
 const similarity = (arr, values) => arr.filter(v => values.includes(v));