[DOCS] swap extra_headers for headers in updated sdk docs

[burtenshaw]

This PR passes the extra headers pass to Argilla down to the http client so that argilla sdk can be used with authenticate deployment like provate HF spaces.

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested

Checklist

• I added relevant documentation
• follows the style guidelines of this project
• I did a self-review of my code
• I made corresponding changes to the documentation
• I confirm My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[davidberenstein1957]

LFTM! One remark, are we testing this flow somewhere, otherwise we can update it?

[burtenshaw]

LFTM! One remark, are we testing this flow somewhere, otherwise we can update it?

No. I could unit test the client attribute.

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[burtenshaw]

@davidberenstein1957 Thanks for pointing me to testing. On closer inspection I realised that the docs were wrong and we should be using headers not extra_headers.

@frascuchon can you confirm this please?

[frascuchon]

@davidberenstein1957 Thanks for pointing me to testing. On closer inspection I realised that the docs were wrong and we should be using headers not extra_headers.

@frascuchon can you confirm this please?

Yes, @burtenshaw. the Argilla client exposes the httpx.Cient init args in the extra kwargs. Let us add some docs to the Argilla.init describing this (as we do with the APIClient definition

[frascuchon]

We already have some unit tests checking this https://github.com/argilla-io/argilla/blob/fix/extra-headers/argilla/tests/unit/api/http/test_http_client.py