Improve description, don't just say it's "$app for Yunohost" which is… (cf https://github.com/YunoHost-Apps/zabbix_ynh/pull/9)

manifest.json

@@ -3,8 +3,8 @@
     "id": "zabbix",
     "packaging_format": 1,
     "description": {
-        "en": "YunoHost port for Zabbix",
-        "fr": "Zabbix pour Yunohost"
+        "en": "A monitoring tool for diverse IT components, including networks, servers, VMs and cloud services.",
+        "fr": "Un outil pour monitorer des réseaux, des serveurs, des VMs et autres services en ligne"
     },
     "version": "2.0",
     "url": "https://www.zabbix.com",