Add `@MustBeDocumented` to `MiraiInternalAPI` and `MiraiExperimentalAPI`

mirai-core/src/commonMain/kotlin/net.mamoe.mirai/utils/Annotations.kt

@@ -23,6 +23,7 @@ import kotlin.annotation.AnnotationTarget.*
     CLASS, TYPEALIAS, FUNCTION, PROPERTY, FIELD, CONSTRUCTOR,
     CLASS, FUNCTION, PROPERTY
 )
+@MustBeDocumented
 annotation class MiraiInternalAPI(
     val message: String = ""
 )
@@ -36,6 +37,7 @@ annotation class MiraiInternalAPI(
 @Retention(AnnotationRetention.SOURCE)
 @RequiresOptIn(level = RequiresOptIn.Level.WARNING)
 @Target(CLASS, TYPEALIAS, FUNCTION, PROPERTY, FIELD, CONSTRUCTOR)
+@MustBeDocumented
 annotation class MiraiExperimentalAPI(
     val message: String = ""
 )