Newer versions of git promote the use of git restore in the help messages in favor of the git checkout command I believe.
git-restore is about restoring files in the working tree from either the index or another commit.
E.g:
> git status
On branch master
Your branch is ahead of 'origin/master' by 124 commits.
(use "git push" to publish your local commits)
Changes to be committed:
(use "git restore --staged <file>..." to unstage)
modified: nvim/.config/nvim/lua/usr/plugins/init.lua
Would be nice if you update the guide with this recent change.