more changes for #13865: fix formatting, rename the function, add comment and add a readme entry

- Eased resolution restriction: generated image's dimensions must be a multiple of 8 rather than 64

- Now with a license!

- Reorder elements in the UI from settings screen

- [Segmind Stable Diffusion](https://huggingface.co/segmind/SSD-1B) support

## Installation and Running

Make sure the required [dependencies](https://github.com/AUTOMATIC1111/stable-diffusion-webui/wiki/Dependencies) are met and follow the instructions available for:

            errors.display(e, "applying cross attention optimization")

            undo_optimizations()

    def conv_ssd(self, m):

    def convert_sdxl_to_ssd(self, m):

        """Converts an SDXL model to a Segmind Stable Diffusion model (see https://huggingface.co/segmind/SSD-1B)"""

        delattr(m.model.diffusion_model.middle_block, '1')

        delattr(m.model.diffusion_model.middle_block, '2')

        for i in ['9', '8', '7', '6', '5', '4']:

        sd_models_xl.extend_sdxl(model)

    if model.is_ssd:

        sd_hijack.model_hijack.conv_ssd(model)

        sd_hijack.model_hijack.convert_sdxl_to_ssd(model)

    if shared.opts.sd_checkpoint_cache > 0:

        # cache newly loaded model