add a mongodb user as admin code example

Example 1: mongodb add user

use 
db.createUser({
  user: '',
  pwd: passwordPrompt(),
  roles: [{
    role: 'readWrite',
    db: ''
  }]
})

Example 2: mongodb add admin user

use admin
db.createUser({
  user: "username",
  pwd: "password",
  roles: [ "root" ]
})