Support of annotation constructor

[BlondeHex]

Could you consider adding the constructor information to the annotations? After version 1.6.0 it became possible to instance an annotation: https://youtrack.jetbrains.com/issue/KT-45395
I'm not sure if this is necessary, but it might be worth doing.

[zarechenskiy]

A little more detail. Right now annotation classes can be instantiated via a constructor call, the constructor of an annotation class can even be declared explicitly in the code: annotation class FooBar constructor(), so it seems quite natural to show the constructor signature in generated documentation.

[IgnatBeresnev]

It was a conscious decision to remove annotation constructors in 1.7.20 (#2576), aside from the primary constructor which is still displayed.

dokka/plugins/base/src/main/kotlin/translators/documentables/DefaultPageCreator.kt

Line 760 in 9559158

internal fun List<Documentable>.shouldDocumentConstructors() = !this.any { it is DAnnotation }

As far as I remember, the main reasoning was that annotations might have constructors to substitute reflection invocations and for internal/compiler purposes, but they are not expected to be documented and instantiated directly under normal circumstances.

If it hurts the feature adoption, I personally don't mind bringing it back (although the annotation pages are somewhat cleaner without constructors), but the change was made after @qwwdfsad brought it up, so maybe Vsevolod has something to say about it :)