Add notebook doc img2img (#2472)
* convert img2img.mdx into notebook doc
* fix
* Update docs/source/en/using-diffusers/img2img.mdx
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
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Co-authored-by: yiyixuxu <yixu@yis-macbook-pro.lan>
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
