auth_email_signup_user incorrect documentation

Using the Moodle Webservices I found a problem in the documentation, related to the "auth_email_signup_user" function.
In particular, the problem concerns the "customprofilefields" parameter, ("User custom fields (also known as user profile fields)").

1. First of all, if the customfield to be used is not set to be shown in the signup page (Site administration > Users > Accounts > User profile fields go to custom field settings and set to "Yes" the "Display on signup page?" option), the call to the webservice generates an error. This is not stated in the documentation.
2. Furthermore, the field relating to the name of the customfield (eg. "customprofilefields [0] [name]") must not contain the name of the field, as the documentation states, but the term "profile_field_" with the final addition of the field shortname .

For example, if we want to use a custom field named "Gender" and with shortname "gender", the term to use is "profile_field_gender" and not only "Gender".

Please correct the docs or tell me how can I do it. Thank you all!