API docs for Custom Playlist Cover Image need updating

[n-j-o]

Neither the API Reference or Console make any reference to how an image should be defined when using PUT /v1/playlists/playlist_id/images to replace the image used to represent a specific playlist.

Specifically, many other API services would permit (or require) a imageUrl or other to be set, instead of the file being passed as binary in the request itself so omitting to provide any reference to how an image should be sent with a request is confusing. 

The API Reference also doesn't provide any information on filetypes / sizes / dimensions that are permissible, and similarly the Console enables you to make a request but provides no ability to actually upload an image (making it pointless)

We have successfully implemented this endpoint in our app using Spotipy, but to date, I've been unable to make a successful request to this endpoint using Postman.. It just returns '400 Bad Request'. I'm assuming there is an issue with the file I'm uploading or the method through which its being sent, but without clearer documentation or better error messages, I'm at a dead end. 

API Reference: https://developer.spotify.com/documentation/web-api/reference/#/operations/upload-custom-playlist-co...

Console: https://developer.spotify.com/console/get-playlist-images/