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/runPromisesInSeries.md

@@ -2,7 +2,7 @@
 
 Runs an array of promises in series.
 
-Use `Array.reduce()` to create a promise chain, where each promise returns the next promise when resolved.
+Use `Array.prototype.reduce()` to create a promise chain, where each promise returns the next promise when resolved.
 
 ```js
 const runPromisesInSeries = ps => ps.reduce((p, next) => p.then(next), Promise.resolve());