Sure, pick away.

I know it's a breaking change, but it shouldn't be too bad for users.

I think the addition of a "drafts" level makes it easier to understand the intention and behavior.

Another option might be to deprecate the 'exclude_docs' setting and rename what 'exclude_docs' is doing in this PR to 'ignore'?

That way folks using 'exclude_docs' will get a warning.

@oprypin
Not quite - I updated the code to what I was thinking. Deprecate exclude_docs and new ignore and drafts settings.

I think the drafts functionality is good to keep.

The issue is that there isn't an additional way to ignore files in the docs_dir, so files we wanted to ignore were included in serve. I think this change appropriately decouples those concepts and opens the door to a couple of new features you might consider in the future:

1. Unblocking setting docs_dir from the root directory Support docs from the root directory. #3450
2. Supporting a command line flag to include drafts or not on serve (by updating the is_in_serve function based on this flag)
3. Supporting a .mkdocsignore type file to locally specify additional ignore patterns (I do this in my plugin and have found it useful)

Let me know if you have any more nit picks!

I could "move" the exclude_docs option to either ignore or draft. I wasn't sure which use case was more popular, so I just went full deprecation so folks would be aware of a breaking change.

Thanks for the discussion, it's been a pleasure. I'll update my other PR after this one merges.