faq: update regions, supported runtimes, instance sizes and Kubernetes

[mehdi653]

Summary

Several answers in the FAQ describe the platform as it was several years ago:

• "Where are my applications and add-ons located?" said Paris or Montreal only. The platform currently exposes many deployment zones (GET /v2/products/zones), and the changelog announced Gravelines HDS (2024) and London on IONOS (2025). Related: No documentation page lists the available deployment regions/zones #989 (no dedicated regions page yet).
• The supported languages list was missing .NET, Elixir, FrankenPHP, Meteor.js, V, static sites and Bun, all documented under /doc/applications/.
• "What is a Scaler?" said sizes go "from pico to XL"; flavors go up to 3XL.
• "I want to run Kubernetes..." still said it was not possible / on the Roadmap, while managed Kubernetes is documented and shipped.

Changes

• Rewrite the locations answer around the current multi-region reality (kept deliberately non-exhaustive so it does not go stale again); points toward a future regions page (No documentation page lists the available deployment regions/zones #989)
• Sync the languages list with the runtimes documented in /doc/applications/, and link to it as the source of truth
• "pico to XL" -> "pico to 3XL", and capitalize "Scalers" at the start of the sentence
• Update the Kubernetes FAQ answer to point to the current docs/product pages, and fix the "CLoud" typo
• Fix the "I want to user Clever Cloud..." typo -> "use"

Test plan

• Preview the FAQ page and check Scaler / languages / locations / Kubernetes answers
• Confirm links to /doc/applications/, /doc/kubernetes/, and the product page resolve