Drop redundant comment to OptIn annotation class

libraries/stdlib/src/kotlin/annotations/OptIn.kt

@@ -47,8 +47,6 @@ public annotation class RequiresOptIn(
 /**
  * Allows to use the API denoted by the given markers in the annotated file, declaration, or expression.
  * If a declaration is annotated with [OptIn], its usages are **not** required to opt in to that API.
- *
- * This class requires opt-in itself and can only be used with the compiler argument `-opt-in=kotlin.RequiresOptIn`.
  */
 @Target(
     CLASS, PROPERTY, LOCAL_VARIABLE, VALUE_PARAMETER, CONSTRUCTOR, FUNCTION, PROPERTY_GETTER, PROPERTY_SETTER, EXPRESSION, FILE, TYPEALIAS