Publish fr feed

doc/feed/1.1/feed-fr.json

+{
+  "version": "https://jsonfeed.org/version/1.1",
+  "title": "Actualités",
+  "user_comment": "Ce fichier redirige vers le forum Duniter (via 'next_url')",
+  "feed_url": "https://raw.githubusercontent.com/duniter/cesium/master/doc/feed/1.1/feed-fr-FR.json",
+
+  "home_page_url": "https://forum.duniter.org/t/nouvelle-version-de-cesium-fr/11458/2",
+  "next_url": "https://forum.duniter.org/t/nouvelle-version-de-cesium-fr/11458/2.json"
+}