Clarify consent management functionality included in CAMARA-API-access-and-user-consent.md

[bhjelm]

Problem description
It's not clear what consent management functionality is included in the section User Authentication/Authorization & Consent Management in CAMARA-API-access-and-user-consent.md.

Expected action
Clearly state the functionality included (in scope) for User Authentication/Authorization & Consent Management.

Additional context
A suggestion would be to review Section 3.1, of the Grant Management for OAuth 2.0 specification, that outlines the various use cases (and actions) supported (such as issuing, updating and revoking consent).

[jpengar]

As stated in #88, we are in the process of finalizing a first release v0.1 of the documentation with the existing agreements. But apart from that, from Telefónica side, we are more than happy if you guys contribute with a PR to the documentation once the v0.1 release is closed, to add the suggested improvement for everyone to review.