[docs] Replace List with built‑in list (PEP 585)

[gacheiro]

Updated the docs to replace typing.List with the built‑in generic list (PEP 585). The example would not work if someone copied and pasted it.

[gacheiro]

Thanks for merging it, @ilevkivskyi!
I’m participating in the Hacktoberfest, could you please add the hacktoberfest-accepted tag to this PR?

[ilevkivskyi]

I don't think we have such a tag, also no one needed it before. Is this some kind of a new requirement this year or something?

[gacheiro]

Ops sorry I meant label instead of tag
Yes, it's required since the project itself does not have the hacktoberfest label
Thanks anyway!

[ilevkivskyi]

OK, I added the label, hopefully we will not get any spam PRs because of this :-)