♻️ Use F-strings in Click examples in docs

[svlandeg]

As discussed in #502 (comment):

This PR covers too many different things, so it would be better to split it to be able to take some things while not taking others.

Specifically, I would take the changes in the Click examples from "some str {blah}".format(blah=blah) to f-strings. That was just an exact copy of Click's tutorials, but now they updated them, we can update them here as well.

Thanks to @marksmayo for originally catching these cases 🙏

[github-actions]

📝 Docs preview for commit 6437826 at: https://114d8aa1.typertiangolo.pages.dev

[github-actions]

📝 Docs preview for commit 8bb1882 at: https://64482858.typertiangolo.pages.dev

[svlandeg]

Note that if we end up merging #938, we can simply close this one. Or we can merge this one first, and update the other one afterwards 🤷.

[tiangolo]

Nice, thank you! 🚀 🍰