fix(bring-your-own-{image,linux}): clarify config drive options and cloud-init expectation

[sbraz]

What type of Pull Request is this?

• Update of existing guide(s)
• Fix

Description

• fix(bring-your-own-{image,linux}): clarify configDriveMetadata field

  The previous "Custom Cloud-Init metadata" wording did not say where the
  values land or how to use them. Clarify that configDriveMetadata is the
  equivalent of OpenStack's server create --property k=v and that the pairs
  appear in the config drive's meta_data.json under the meta key, with a
  concrete example and a link to the OpenStack metadata service schema.

  Ref: PUBM-52977

  Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

• fix(bring-your-own-{image,linux}): clarify configDriveUserData field

  The previous "Your configDrive file content" wording was unclear about what
  the field actually is. Rename it to "cloud-init user-data" and extend the
  footnote to say it's standard cloud-init user-data (the equivalent of
  OpenStack's server create --user-data <file>), with a link to the
  upstream cloud-init format documentation.

  Ref: PUBM-52977

  Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

• fix(bring-your-own-{image,linux}): drop possessive in deployment-options table

  Only 4 of 9 customizations rows used "Your"/"votre" — the rest were already
  phrased as bare noun labels ("Hostname", "EFI bootloader path",
  "HTTP Headers key", etc). Drop the outliers to align: "Your image URL" →
  "Image URL", "L'URL de votre image" → "L'URL de l'image", and so on.
  Also drops a stray trailing period in BYOI fr-fr's imageCheckSumType row.

  Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

• fix(bring-your-own-{image,linux}): clarify config drive documentation

  Rewrite the misleading "default vs custom" [!primary] callout near
  the deployment-options table (configDriveUserData is purely
  additive, not a toggle between two pre-built config drives) into a
  factual paragraph on what OVHcloud creates during install and how
  configDriveUserData fits in. BYOL: config drive is always added;
  BYOI: only added when at least one customization on the page is
  set, otherwise no config drive is created.

  Add a separate brief prerequisite [!primary] in Requirements
  stating that to apply OVHcloud customizations at first boot, the
  image must include cloud-init or a compatible alternative (such as
  FreeBSD's nuageinit).

  Normalize prose to cloud-init upstream conventions ("ConfigDrive"
  -> "config drive", "Cloud-Init" -> "cloud-init"; API field names
  like configDriveUserData are unchanged), update an outdated 22.1_a
  documentation URL, and fold the cloud-init examples link into
  footnote 1 where configDriveUserData is defined.

  Co-Authored-By: Claude Opus 4.7 (1M context) noreply@anthropic.com

Mandatory information

The translations in this Pull Request have been done using:

• Other tool (specify which tool was used): Claude Code (Opus 4.7)
• This Pull Request can be merged as soon as possible.
• This Pull Request content should be replicated for the US OVHcloud documentation: YES

[benchbzh]

Thank you for your contribution @sbraz!