Update Readme to make setup easier

[TheDiren]

When trying to setup the app I struggled with some of the steps, maybe it would be nice to have more information about that in the readme:

• Influx 2.0
  When starting of with a Influx 2.0 databases, without migrating, how do I create user credentials? Databases do not exist anymore, how do I create a bucket and how do I connect to the bucket?
  The syntax to create a new user changed to:

influx user create -n user_influx -p pass_influx -o BEEP

However, I run into a problem when running this, maybe related to: https://community.influxdata.com/t/create-user-fail-with-error-write-users-is-unauthorized/20509

• Admin-backend
  Is the link api.[your_domain]/webapp#!/login/create still the correct one to use?