Provide the path to download the ISO in the installation documentation

[brembelguebli]

Component:

Metalk8s Documentation

Why this is needed:

The URL to download the ISO

What should be done:

Provide the URL for the ISO download, at least for the current version

Implementation proposal (strongly recommended):

Test plan:

[NicolasT]

We are not publicly distributing pre-built versions of MetalK8s and don't plan to do so. Hence, any such links must be in Scality-specific documentation, not in the open-source project documentation.