Improve the Home Page

The home page hasn't had any changes done since the beginning of CloudNativePG.
There are many relevant pieces of info that we could be reflecting here.
E.g. Volume snapshots. Kubecon talks. OpenShift certification

The content we do have there is spread out and somewhat generic.
Maybe we should have a compact table with a feature listing, which could start in the first screenful.

Start at the website home page and review how its current content is spread across the first screenful. Inventory the relevant information mentioned in the issue, including volume snapshots, KubeCon talks, OpenShift certification, and existing feature content. Done means the page presents a compact, clear feature listing and more focused current information.

Written by the indexing model from the issue text.