Request: Include a link to this repo at the bottom of the docs page

I think that we could get more people to contribute doc improvements if at the bottom of the official docs page (e.g. pages like https://docs.atuin.sh/configuration/config/#sync_address) there was a blurb similar to "Contribute to these docs at https://github.com/atuinsh/docs/blob/main/src/content/docs/configuration/config.mdx")

Also it was a little harder finding these docs because the main atuin repo (https://github.com/atuinsh/atuin/) _does_ have a `docs/` folder, but it only includes non-english docs and doesn't link here.

Start with the official docs page linked in the issue and the example source file at src/content/docs/configuration/config.mdx. Find the shared page layout or footer used by these pages, add the repository contribution link there, and verify that it appears at the bottom of the rendered configuration page.

Written by the indexing model from the issue text.