JJ: Description from the destination commit:

rm offline_sig.ml

JJ: Description from source commit:
.

tools/offline.ml

@@ -1,5 +1,5 @@
 (* TODO
-   change download_cmd/upload_cmd
+   better cmd doc
    change arguments: '_' -> '-'
 
    all management operations:
@@ -99,8 +99,8 @@ let download_cmd =
   let doc = "GET" in
   Cmd.make (Cmd.info "download" ~doc)
   @@
-  let+ output = output in
-  download ~output
+  let+ output = output and+ url = url in
+  download ~output ~url
 
 let upload_cmd =
   let doc = "POST" in