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/sortedIndexBy.md

@@ -3,7 +3,7 @@
 Returns the lowest index at which value should be inserted into array in order to maintain its sort order, based on a provided iterator function.
 
 Check if the array is sorted in descending order (loosely).
-Use `Array.findIndex()` to find the appropriate index where the element should be inserted, based on the iterator function `fn`.
+Use `Array.prototype.findIndex()` to find the appropriate index where the element should be inserted, based on the iterator function `fn`.
 
 ```js
 const sortedIndexBy = (arr, n, fn) => {