docs: hero steps, Getting started steps and theme 2.7.0

[franklupo]

The home page shows the steps to a first result, and Getting started holds the same steps, in the same order and with the same words. Theme 2.7.0.

Home page

• Steps panel in the hero, in place of the install panel: Add the package / Create the client / Make the first call / Read some data.
• The motto of the suite under the hero ("By developers, for developers."), then the commands, in code blocks that can be copied.
• An icon on each feature card.

Getting started

• The steps of the hero as numbered steps, each with its title. The text of the steps is the one the page already had.

Every page

• Footer with the motto, the cv4pve suite line and the Proxmox trademark notice.
• No "Edit page" link and no "Last updated" date.

README

• The same closing block as the site footer: motto, suite line, trademark notice, copyright.

Theme

• docs/package-lock.json: cv4pve-docs-theme 2.7.0.

Checked on the site built with theme 2.7.0: internal links and anchors, the hero steps against Getting started, footer and trademark notice on every page.