fix(curriculum): add ternary example to music player step 70 (freeCodeCamp#55706)

Author: kevin-wu01

curriculum/challenges/english/15-javascript-algorithms-and-data-structures-22/learn-basic-string-and-array-methods-by-building-a-music-player/6555d729c9bfd7c3195f1948.md

@@ -18,6 +18,12 @@ const element = document.getElementById('example');
 console.log(element.textContent); // Output: This is some text content
 ```
 
+You can use a ternary operator to conditionally set the text content value. Here is an example of assigning the result of a ternary operator to a variable:
+
+```js
+const example = condition ? "I'm true" : "I'm false";
+```
+
 Use a ternary operator to check if `currentTitle` evaluates to a truthy value. If it does, set `playingSong.textContent` to `currentTitle`. Otherwise, set it to an empty string.
 
 Then below that, use a `ternary` operator to check if `currentArtist` is truthy. If so, set `songArtist.textContent` to `currentArtist`. Otherwise, set it to empty string.