title: nextJS deep dynamic routing
body: <p>While I'm developing with NextJS, I have a question. <br/>
  To Use dynamic routing, we write file like [id].js <br/>
  When my directory structure is like this: <br/>
  pages <br/>
  &emsp;ㄴ area <br/> 
  &emsp;&emsp; ㄴ [area].js ,br/></p>
  
  <p>page example is like 'area/texas' or 'area/newyork' <br/>
  <br/></p>
  
  <p>I want to double dynamic routing like 'area/texas/houston' or 'area/texas/dallas' <br/>
  (page/area/region, area and region can change)<br/>
  But I don't know how to make file structure <br/>
  I tried a few way, I failed :-( <br/>
  <br />
  Let me know, how to make structure!!</p>