"Registration/login only challenge" typos in WebAuthn Guide

[primozh]

Description

In the WebAuthn guide there is an issue with the documentation about Javascript loginOnly function. Title of the subchapter should be changed and also in the code example function used is not the one mentioned in the text.

Suggested change

=== Only invoke the registration challenge and authenticator

The `webAuthn.loginOnly` method invokes the login challenge endpoint, then calls the authenticator and returns 
a https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise[Promise object] containing a
JSON object suitable for being sent to the callback endpoint. You can use that JSON object in order to store the credentials
in hidden form `input` elements, for example, and send it as part of a regular HTML form: 

[source,javascript]
----
webAuthn.login({ name: userName })

Should be changed to "Only invoke the login challenge..." and "webAuth.loginOnly({ name: userName })"

[geoand]

@primozh would you be interested in providing a fix?

[primozh]

@geoand sure, I'll prepare a PR