Update 'README.md'

fix #1

README.md

@@ -68,7 +68,7 @@ var greenlock = require('greenlock-koa').create({
 var http = require('http');
 var https = require('https');
 var koa = require('koa');
-var app = koa();
+var app = new koa();
 
 app.use(function *() {
   this.body = 'Hello World';
@@ -84,7 +84,7 @@ server.listen(443, function () {
 
 // http redirect to https
 var http = require('http');
-var redirectHttps = koa().use(require('koa-sslify')()).callback();
+var redirectHttps = app.use(require('koa-sslify')()).callback();
 http.createServer(greenlock.middleware(redirectHttps)).listen(80, function () {
   console.log('Listening on port 80 to handle ACME http-01 challenge and redirect to https');
 });