docs: Fixed variables in f-strings (#20087)
* docs: Fixed variables in f-strings
* Replace unknown `block` with known `block_type` in ValueError
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>
* Add missing torch import in docs code block
Co-authored-by: Sylvain Gugger <35901082+sgugger@users.noreply.github.com>