Fix in multer configuration (Storage)

[psimanta]

I tried with settings mentioned in the README.md file. If I use the slash like this /tmp it refers my c drive, but if I don't use slash it works.

[LinusU]

The intention of the example was to put the file in the root temp folder, so I'm not sure that this is the best approach 🤔

Maybe switch it to use something like: path.join(os.tmpdir(), 'my-uploads')?