fix(docs): remove unused method (#39)

Author: kobenguyent

README.md

@@ -32,8 +32,6 @@ Use this helper in your tests to check email interactions. The most popular one
 
 ```js
 const mailbox = await I.haveNewMailbox();
-// register user on a website
-I.registerUser(mailbox.emailAddress);
 // wait 10 seconds for an email
 const email = await I.waitForLatestEmail(10);
 I.seeInEmailSubject('Restore Password');