[Docs] Add "Feature Matrix" or "Capability Status" table to Provider pages

### Is your feature request related to a problem? Please describe.
Currently, the "Supported Providers" documentation lists which drivers exist (e.g., EC2, Azure ARM, GCE), but it is difficult for a user to determine the **depth of support** for each provider without diving into the source code.

**The Problem:**
A user looking at the [Compute Providers page](https://libcloud.apache.org/supported_providers.html) sees that "Amazon EC2" is supported. However, they cannot easily verify:
1. Does it support recent features like IMDSv2 (Instance Metadata Service v2)?
2. Does it support Spot Instance requests via the unified API?
3. Are the `list_sizes` or `list_images` methods hardcoded or dynamically fetched?

This opacity makes it hard for architects to evaluate Libcloud against the native SDKs (Boto3, Azure SDK) for their specific needs.

### Describe the solution you'd like
I propose enhancing the documentation for major providers (Compute/Storage) to include a **Capability Status Matrix**.

**Proposed Documentation Update:**
On the individual provider pages (or a centralized matrix), we should track the support status of standard API methods.

*Example Table:*
| Feature | Support Status | Notes |
| :--- | :--- | :--- |
| `create_node` | ✅ Full | Supports user_data, SSH keys |
| `list_sizes` | ⚠️ Partial | Hardcoded list (last updated 2024) |
| `deploy_node` | ✅ Full | |
| `ex_start_node` | ✅ Extension | Provider-specific extension |
| `IPv6 Support` | ❌ No | |

### Describe alternatives you've considered
* **Status Quo:** Users must install the library and run `dir(driver)` or inspect the source code to find capabilities.
* **Automated Badge:** Generating this matrix automatically from the test suite (e.g., based on which methods are overridden in the driver class). This would be the ideal long-term solution.

### Additional Context
As cloud providers add features rapidly, Libcloud's value proposition is "unification." Clear documentation on *what* is unified vs. what requires extension methods (`ex_*`) is critical for adoption.

Commencez par la page « Supported Providers » à l’adresse libcloud.apache.org/supported_providers.html et examinez les pages individuelles des fournisseurs Compute et Storage. Déterminez si la matrice doit figurer sur les pages des fournisseurs ou dans un document centralisé, puis recensez les méthodes standard et les extensions ex_* spécifiques aux fournisseurs dans les drivers concernés. Le travail est considéré comme terminé lorsque les principaux fournisseurs sélectionnés disposent de statuts de prise en charge et de notes documentés, et que le périmètre ainsi que l’approche de maintenance sont explicitement définis.

Rédigé par le modèle d'indexation à partir du texte de l'issue.