content(resources): clean up placeholder resources

src/content/resources/javascript/promises/intro.md

@@ -101,7 +101,3 @@ getCharacters().then(characters => {
   console.log(characters); // (20) [{...}, {...}, {...}]
 });
 ```
-
-Let's break down what's happening in this function
-
-// TODO: finish this

src/content/resources/javascript/promises/simplifying-promises.md

@@ -5,8 +5,6 @@ created_at: "2019/07/26"
 title: Simplifying Promises
 ---
 
--- placeholder --
-
 The first naive attempt, using new Promise for something that already returns a promise.
 
 ```js