Fix code in `Scala Tour > Singleton Objects > Companion Objects`#2911

Philippus merged 2 commits intoscala:mainscala/docs.scala-lang:mainfrom

VMironiuk:fix/scala-tutorial/singleton-objects/companion-objects-codeVMironiuk/docs.scala-lang:fix/scala-tutorial/singleton-objects/companion-objects-codeCopy head branch name to clipboard