scalafix-check-scaladoc is a custom scalafix lint rule that examines scaladoc comments on classes, methods, values, type definitions, and so on.
It complains if they are visible from scalafix-check-scaladoc (it examines only public APIs by default) and are missing scaladoc comments.
To permanently install the rule for a build, users can add the dependency to build.sbt by updating scalafixDependencies in ThisBuild.
// build.sbt
scalafixDependencies in ThisBuild +=
  "com.github.tanishiking" %% "scalafix-check-scaladoc" % "0.0.2"Now CheckScaladoc is available.
// sbt shell
> scalafix CheckScaladoc
or configure in .scalafix.conf
rules = [
  CheckScaladoc
]
CheckScaladoc.files = ["src/main/scala/path/to/target/dir"]
and run > scalafix (on sbt shell).
MyCode.scala:45:1: error: [CheckScaladoc] case object Test doesn't have scaladoc
[error] case object Test
[error] ^^^^^^^^^^^^^^^^/** This object won't be complained because it has a scaladoc comment
  */
object Test {
  val value = 1 // this will be complained because it doesn't have scaladoc comment
  /** This won't be complained
    */
  var valueWithScaladoc = 1
  // this won't be complained even though it doesn't have scaladoc comment
  // because privateVal is private and scalafix-check-scaladoc examines
  // only on public APIs.
  private val privateVal = 1
}| Name | Description | Default | 
|---|---|---|
| access | Access modifier that allow scalafix-check-scaladoc to lint the API. For example, if access=protected, scalafix-check-scladoc examines on public or protected APIs. | public | 
| files | Files or dictionaries to lint | [] | 
| requireDocOnInherited | If requireDocOnInherited=true, scalafix-check-scaladoc will examines on inherited methods. | false |