Update endpoint description to reflect all use cases

[fernandopradocabrillo]

What type of PR is this?

Add one of the following kinds:

• documentation

What this PR does / why we need it:

Improve endpoint documentation to reflect the functionality and all possible usecases as well as when idDocument related errors are returned.
Updates derive from discussion on #135

Which issue(s) this PR fixes:

Fixes #135

Special notes for reviewers:

Changelog input

 release-note

Additional documentation

This section can be blank.

docs

[GillesInnov35]

Thanks

[GillesInnov35]

@fernandopradocabrillo , at Orange idDocument field is not currently proposed in the match identity API. but I understand that it is a second level of control of identity for some providers.
I think that idDocument field should be associated to a documentType (according to what is specifiedin partyManagement TMF API).
I read few comments concerning a list document type, it would be interesting to work on this point .
BR
Gilles

[ToshiWakayama-KDDI]

Hi @GillesInnov35 , @fernandopradocabrillo ,

I have just updated the proposal to add 'in those cases' to line 24, to make it aligned with line 76.

Hope this is OK, and I would like Gilles to approve this PR again.

Thanks.
Toshi

[GillesInnov35]

Thanks