doc: add internal functionality details of util.inherits

PR-URL: nodejs#24755
Reviewed-By: Joyee Cheung <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Matteo Collina <[email protected]>

Author: BridgeAR

doc/api/util.md

@@ -332,6 +332,8 @@ Inherit the prototype methods from one [constructor][] into another. The
 prototype of `constructor` will be set to a new object created from
 `superConstructor`.
 
+This mainly adds some input validation on top of
+`Object.setPrototypeOf(constructor.prototype, superConstructor.prototype)`.
 As an additional convenience, `superConstructor` will be accessible
 through the `constructor.super_` property.