fix: update let section

jsjoeio · web-flow · commit 6d404a06ec06 · 2019-10-03T15:27:42.000-07:00
The section on `let` feels outdated. 

&gt; The `let` keyword is actually a newer JavaScript construct that TypeScript makes available.

I rewrote it based on my best solution but hoping to get feedback :)
diff --git a/pages/Basic Types.md b/pages/Basic Types.md
@@ -288,5 +288,5 @@ Using one over the other is mostly a choice of preference; however, when using T
 # A note about `let`
 
 You may've noticed that so far, we've been using the `let` keyword instead of JavaScript's `var` keyword which you might be more familiar with.
-The `let` keyword is actually a newer JavaScript construct that TypeScript makes available.
+The `let` keyword was introduced to JavaScript in ES2015 and is now considered the standard because it's safer than `var`.
 We'll discuss the details later, but many common problems in JavaScript are alleviated by using `let`, so you should use it instead of `var` whenever possible.
