refactor: change images directory

layouts/mentions-legales/section.html

layouts/notre-demarche/section.html

layouts/notre-ecosysteme/section.html

layouts/notre-impact/section.html

layouts/notre-posture/section.html

layouts/partials/footer.html

layouts/partials/header.html

layouts/services-libres/section.html

static/img/demarche/accompagnement.svg

static/img/demarche/choix-des-outils.svg

static/img/demarche/evolution.svg

static/img/demarche/implementation.svg

static/img/demarche/problematique.svg

static/img/icon.png

static/img/impact/le_filament_impact_clients.svg

static/img/impact/le_filament_impact_fournisseurs.svg

static/img/impact/le_filament_impact_salaries.svg

static/img/impact/le_filament_impact_societe.svg

static/img/impact/le_filament_impact_usagers.svg

static/img/license-cc-by-sa.png