update README on new user command

README.md

@@ -26,7 +26,7 @@ For getting a development version of Fathom up & running, go through the followi
 1. Get code: `git clone https://github.com/usefathom/fathom.git $GOPATH/src/github.com/usefathom/fathom` 
 1. Compile into binary & prepare assets: `make build` 
 1. (Optional) Set your [custom configuration values](https://github.com/usefathom/fathom/wiki/Configuration-file).
-1. Register your user account: `fathom register --email=<email> --password=<password>`
+1. Register your user account: `fathom user add --email=<email> --password=<password>`
 1. Start the webserver: `fathom server` and then visit **http://localhost:8080** to access your analytics dashboard.
 
 To install and run Fathom in production, [have a look at the installation instructions](https://github.com/usefathom/fathom/wiki/Installing-&-running-Fathom).