update README

readme.md

@@ -22,19 +22,20 @@ app.engine('jade',function(view,locals){
   return function(done){
     jade.renderFile(view,locals,done);
   };
-})
+});
 ```
 
 app.engine('ext',engine);
-engine should be a thunk or a Promise;
+engine should return a thunk or a Promise
+so use `Promise.promisify` with bluebird is also supported.
 
 ## Why
 why not [koa-views](https://github.com/queckezz/koa-views)?
 
 koa-views -> [co-views](https://github.com/tj/co-views) -> [co-render](https://github.com/tj/co-render)
 -> [consolidate.js](https://github.com/tj/consolidate.js)
 
-And only engine supported in consolidate.js supported in koa-views;
+Any engine not supported in consolidate need to PR to consolidate.I hate centerlized.
 
 ## License
 MIT http://magicdawn.mit-license.org