[docs] typo in AutoencoderOobleck docs

[ivnvalex]

Docs for AutoencoderOobleck have duplicated OobleckDecoderOutput descriptions

https://huggingface.co/docs/diffusers/api/models/autoencoder_oobleck#autoencoderoobleck
https://github.com/huggingface/diffusers/blob/0f1abc4ae8b0eb2a3b40e82a310507281144c423/docs/source/en/api/models/autoencoder_oobleck.md