Line highlighting

Orginally markdown doesn't have supporting for highlighting lines inside codeblock. However, Dimer allows it with it's own custom syntax.

You need to wrap line numbers inside curly braces as shown below.


```js{2,5-7}
const http = require('http')
const bodyParser = require('body-parser')

http.createServer((req, res) => {
  bodyParser.parse(req, (error, body) => {
    res.end(body)
  })
}).listen(3000)
```