Update API according to the latest implementation in Parser-JS

[smoya]

Reason/Context

@jonaslagoni and @smoya have been working on a new iteration of the current Parser-API by directly implementing a POC on the current Parser-JS.

It can be found here: asyncapi/parser-js#453

This means, that implementation has a more up-to-date API than the current in this repository, a validated API that can be implemented without any issue.

Description

To update https://github.com/asyncapi/parser-api/blob/master/docs/v1.md according to asyncapi/parser-js#453.

cc @jonaslagoni @Souvikns @magicmatatjahu