Let deno doc pull default settings from deno.json

[RickCogley]

Currently as of deno 2.4.3, deno doc automatically generates to /docs if I'm understanding correctly. You can control the output directory with cli switches well enough, but it would be really useful to be able to control the output folder via some setting in deno.json which I don't think is possible at this time. At least I can't find anything about that in the docs page for it.

For example, talking about a use case, /docs is a logical place for various docs in a repository, so I have been storing various md files in there, and generating via deno doc outputting to /docs/api. I made a mistake running it as deno doc --html and that clobbered my /docs folder, so, I think it would be useful to be able to specify its default output folder in deno.json. That way, even if I dumbly leave off the switch, it will generate where I want it to.