v1 release exports router instead of UI

[k2s]

Examples for v1 tag show const { UI } = require('bull-board'), but UI is never exported from bull-board/dist/index.js, it exports router, which works.

[felixmosh]

It is a major release, we decided to change the interface a bit.

Instead of invoking UI function, you get the router which is what UI() was returning, check the usage in example.js

[vcapretz]

PR up for updating the readme file! thanks for the catch @k2s 👍