Fine tune docs for upload URL

I _believe_ (someone please check/confirm) that the URL **always** needs
to end in `/file`.  It's not just something constrained to this example.

doc/user/packages/terraform_module_registry/index.md

@@ -41,7 +41,7 @@ PUT /projects/:id/packages/terraform/modules/:module-name/:module-system/:module
 
 Provide the file content in the request body.
 
-Note that, in the following example, the request must end with `/file`.
+As the following example shows, requests must end with `/file`.
 If you send a request ending with something else, it results in a 404
 error `{"error":"404 Not Found"}`.