Add madlad-400 MT models (#27471)
* Add madlad-400 models
* Add madlad-400 to the doc table
* Update docs/source/en/model_doc/madlad-400.md
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
* Fill missing details in documentation
* Update docs/source/en/model_doc/madlad-400.md
Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
* Do not doctest madlad-400
Tests are timing out.
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Co-authored-by: amyeroberts <22614925+amyeroberts@users.noreply.github.com>
