enrich documentation of output_format_dependency

[atusy]

This PR adds an missing document that guides how to merge a dependency.

BTW, I think it is a good idea to add a practical usage (like the one in #2507) on the function document or somewhere else (maybe R Markdown Cookbook?).
Do you have any suggestions?

[cderv]

BTW, I think it is a good idea to add a practical usage (like the one in #2507) on the function document or somewhere else (maybe R Markdown Cookbook?).

Yes R Markdown cookbook seems to me like a right place. You could also write a blog post (or add to existing one) this example, and we could link from help page too 🤷‍♂️ Just that blog post is usually a good place for examples.

[yihui]

Thanks!

[atusy]

@cderv @yihui

Thank you for the review.
About the documentation, I'd be happy to contribute R Markdown Cookbook.
Just for now, I added the example in the previous blog post.
https://blog.atusy.net/2023/08/28/rmarkdown-output-format-dependency/