[`Docs`] Fix typos and update files at API's Pipelines page 1 (#5744)
* Fix typos, update, add Copyright info, and trim trailing whitespace
* Update alt_diffusion.md
* Remove nonoperational demo
* Update docs/source/en/api/pipelines/consistency_models.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
* Update docs/source/en/api/pipelines/latent_consistency_models.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
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Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>