update openapi.json

Author: Andrei Neagu

services/notifications/openapi.json

@@ -2,7 +2,7 @@
   "openapi": "3.1.0",
   "info": {
     "title": "simcore-service-notifications",
-    "description": "Service for executing commands on docker nodes",
+    "description": "Service used for sending notifications to users via different channels",
     "version": "0.0.1"
   },
   "servers": [