[`Docs`] Fix typos and update files at API's Main Classes, Models, and Schedulers pages (#5720)
* Fix typos, update, add Copyright info, and trim trailing whitespaces
* Update docs/source/en/api/loaders.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
* Update docs/source/en/api/models/autoencoder_tiny.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
* Update docs/source/en/api/models/autoencoder_tiny.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>