Examples redirect to trojan npmserver

Your examples redirect people to trojan sites:

```
$ npm set registry http://npmserver:4873
$ npm adduser --registry http://npmserver:4873 # Keyin your username, password and email
```

`npmserver` is commonly hijacked dns.
Resolution will say something like "npmserver has multiple addresses"

There's various people trying to claim it right now, including `104.239.207.44`
https://www.zingbox.com/wp-content/uploads/2018/01/Lizard-Squad-White-Paper-v7.pdf