update comments

server.js

@@ -62,12 +62,14 @@ app.use('/public', serve('./public', true))
 app.use('/manifest.json', serve('./manifest.json', true))
 app.use('/service-worker.js', serve('./dist/service-worker.js'))
 
-// 1-second microcache.
+// 1-second micro-cache.
+// https://www.nginx.com/blog/benefits-of-microcaching-nginx/
 const pageCache = LRU({
+  max: 100,
   maxAge: 1000
 })
 
-// since this app has no user-specific content, every page is cacheable.
+// since this app has no user-specific content, every page is micro-cacheable.
 // if your app involves user-specific content, you need to implement custom
 // logic to determine whether a request is cacheable based on its url and
 // headers.