Spelling and markdown links checker

[Shaglock]

Since there were a few broken links and typos, maybe it makes sense to use some github actions for spelling and links check, what do you think?
Something like https://cspell.org and https://github.com/UmbrellaDocs/action-linkspector

[Shaglock]

oops I meant to create this issue in https://github.com/TanStack/create-tsrouter-app repo.