Use destructuring and template string for formatDuration (#720)

snippets/formatDuration.md

@@ -19,7 +19,7 @@ const formatDuration = ms => {
   };
   return Object.entries(time)
     .filter(val => val[1] !== 0)
-    .map(val => val[1] + ' ' + (val[1] !== 1 ? val[0] + 's' : val[0]))
+    .map(([key, val]) => `${val} ${key}${val !== 1 ? 's' : ''}`)
     .join(', ');
 };
 ```