[WIP] Revisit documentation

[Wauplin]

This goal of this PR is to track all changes made to documentation in a single place.
The work will be split in multiple smaller PRs. Both todo-list are purely indicative. If anyone sees something to add/remove, feel free to comment or directly do it.

Done in #1233:

• adopt divio framework
• configuration page
• installation page
• make index / quickstart / installation pages consistent
• update href links in index (the 4-cells part)

Done in #1245 and #1249:

• Difference HTTP-based / GIT-based

TODO

• Move existing guides to either guides/ or tutorials/ folders
• add redirections for guides that have been moved to guides folder
• harmonize docstrings (the optional thingy, the <tip> vs raises sections,...)
• Guide to download / upload a model
• HfApi.upload_file vs hf_hub_download vs Repository: what should I use? When?
• How to use endpoints and private models ?
• (?) End to end guide for a MLOps engineer: entire ML lifecycle using just code.
• Manage a repo (create, delete, add tag, add branch, rename, change_visibility,...)
• Manage discussion on a repo (list discussion, reply, change status,...)
• Manage a local clone (Repository object)
• Download a file / a folder / all files (get file metadata, file existence)
• Upload a file, upload a folder, update some files, delete some files
• How to build an integration ? (push_to_hub, from_pretrained) (programmatically, mixin, cli)
• Modelcards
• Inference API
• utils:
  • Make HTTP request
  • Handle cache
  • Runtime
  • Logging
  • Validators
  • TQDM

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint.

[Wauplin]

Most of the task points in the description have now being handled. I'm closing this PR without merging.