cms: optional per-language slug on the FR/EN post collections

public/admin/config.yml

@@ -67,6 +67,7 @@ collections:
     fields:
       - { label: Title, name: title, widget: string }
       - { label: Description, name: description, widget: string, required: false }
+      - { label: Per-language slug, name: slug, widget: string, required: false, pattern: ['^[a-z0-9]+(-[a-z0-9]+)*$', 'Kebab-case: lowercase letters, digits, hyphens'], hint: 'per-language slug; makes /<slug> + /<slug-en> work directly' }
       - { label: Body, name: body, widget: markdown }
     # `{{slug}}` on creation comes from the entry slug editor — type the post's
     # folder name there; opening an existing file always resolves it correctly.
@@ -83,4 +84,5 @@ collections:
     fields:
       - { label: Title, name: title, widget: string }
       - { label: Description, name: description, widget: string, required: false }
+      - { label: Per-language slug, name: slug, widget: string, required: false, pattern: ['^[a-z0-9]+(-[a-z0-9]+)*$', 'Kebab-case: lowercase letters, digits, hyphens'], hint: 'per-language slug; makes /<slug> + /<slug-en> work directly' }
       - { label: Body, name: body, widget: markdown }