Deprecation of overlays in favor of layers API

[abdelrahman-elkady]

According to the docs, overlay transformation will be deprecated on 31st Oct 2023 in favor of the layers API

The current implementation doesn't support the layers API yet as far as I see, I think this needs to be supported and updated in the docs too

[imagekitio]

Please use raw to specify the layer transformation - https://github.com/imagekit-developer/imagekit-nodejs#list-of-supported-transformations