feat: method chaining after the init function?

[pratyushgguptaa]

Actually, I wanted to have this functionality:

myRL.init({ prompt: '> ' }).on('line', (line) => {
    //....
  })

Sometimes, we need only one listener and can be done in a single line otherwise we did like this:

const myRL = require('serverline')
 myRL.init({ prompt: '> ' })
  myRL.on('line', (line) => {
    // ...
  })

Instead we can do all of this in a single line:

require('serverline').init({ prompt: '> ' }).on('line', (line) => {
    //...
  })

---

I think we can achieve this using return this from the init function.
I tried (commit) and it works fine for me but is it the right way to do it?

Shall I make a PR or there is a better way to achieve this?