Make Metafooter ready for translations

[remibetin]

Problem

When the metafooter is used (Tutorials resources), some phrases can't be translated because they are hardcoded:

• Updated
• first published
• Editors
• Update Editor
• Contributors

Solution description

• In the file that generates the footer, we use an existing include to make the phrases translatable
• The phrases to translate are added in the translations.yml file

PR opened

• https://github.com/w3c/wai-website-theme/pull/60
• https://github.com/w3c/wai-website-data/pull/104/