docs: add new environment variable to disable Hugging Face warning when spaces persistant storage is disabled

[jfcalvo]

Description

This PR is associated to changes implemented on https://github.com/argilla-io/argilla-server/pull/124 adding a new environment variable to force disable a warning when Argilla is running on Hugging Face Spaces and persistant storage is disabled.

Closes #4736

Type of change

(Please delete options that are not relevant. Remember to title the PR according to the type of change)

• [ ] Bug fix (non-breaking change which fixes an issue)
• [ ] New feature (non-breaking change which adds functionality)
• [ ] Breaking change (fix or feature that would cause existing functionality to not work as expected)
• [ ] Refactor (change restructuring the codebase without changing functionality)
• [ ] Improvement (change adding some improvement to an existing functionality)
• [x] Documentation update

How Has This Been Tested

• [x] Checking that the markdown is correctly rendered.

Checklist

• [x] 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
• [ ] My changes generate no new warnings
• [ ] I have added tests that prove my fix is effective or that my feature works
• [ ] I filled out the contributor form (see text above)
• [ ] I have added relevant notes to the CHANGELOG.md file (See https://keepachangelog.com/)

[frascuchon]

As it is added in HF, maybe a reference should be added here too? https://docs.argilla.io/en/latest/getting_started/installation/deployments/huggingface-spaces.html#setting-up-secret-environment-variables

I think makes more sense adding under the section Setting up the persistent storage

[jfcalvo]

As it is added in HF, maybe a reference should be added here too? https://docs.argilla.io/en/latest/getting_started/installation/deployments/huggingface-spaces.html#setting-up-secret-environment-variables

I think makes more sense adding under the section Setting up the persistent storage

I will add a tip block there.

[jfcalvo]

@sdiazlor added a note section on Hugging Face storage section about the new environment variable. Please feel free to improve it if you think it's not clear enough.

[sdiazlor]

@jfcalvo Thanks, it should be a bit clearer now.