Docs.NoMissing: Add more configuration options

[jfmengels]

This is an issue to gather feedback and ideas.

The Docs.NoMissing rule has some configuration options that I think would work fine for packages, but probably not so much for application projects.

I can't imagine that some projects will require documentation for all functions and types in their project, but there is no concept of exposed modules there, so either this rule will be used there with a lot of ignoreRuleFor*, or it needs more configuration options.

I'm imagining a list of explicit modules or explicit directories, kind of like the following, though I'm not sure this will be sufficient either.

rule =
	{ document = everything
	, from =
        [ moduleNamed "Some.Module"
        , modulesUnder "Some.Folder"
        ]
    }

Alternatively, the rule could take a function ModuleName -> Bool that acts as a predicate, which would be very configurable but also potentially a bit annoying to configure.

I would love to see what options you'd like to have and/or what you think is best!

[gampleman]

I would quite like it to allow blank documentation for types. The main motivating example is:

someFunction : List Attribute -> RequiredInput -> Result

type Attribute

foo : Attribute 

bar : Int -> Attribute

there really isn't a whole lot to say about this type.

[jfmengels]

Sorry, I'm not sure what you mean, can you clarify a bit more? Which type are you referring to?

[gampleman]

The Attribute type in the example. Often times it's fairly impossible to say anything about a type when you have both the consumers and producers well documented without really excessive repetition ("can be constructed with foo or bar and used in someFunction") or terrible triteness ("used to pass optional attributes to functions").