Fix indentation of comments

src/index.js

@@ -9,16 +9,16 @@ expired.in = headers => differenceInMilliseconds(expired.on(headers), new Date()
 expired.on = headers => {
 	const originDate = new Date(headers.date);
 
-  // Get max age ms
+	// Get max age ms
 	let maxAge = headers['cache-control'] && headers['cache-control'].match(/max-age=(\d+)/);
 	maxAge = parseInt(maxAge ? maxAge[1] : 0, 10);
 
-  // Take current age into account
+	// Take current age into account
 	if (headers.age) {
 		maxAge -= headers.age;
 	}
 
-  // Calculate expirey date
+	// Calculate expirey date
 	return addSeconds(new Date(originDate), maxAge);
 };