This is what I got when I wanted to install the "NoIndex before Launch" Add-on to my site (through extendConcrete5 folder's Add Functionality)

"[Semantical Error] The class "Doctrine\ORM\Mapping\Entity" is not annotated with @Annotation. Are you sure this class can be used as annotation? If so, then you need to add @Annotation to the _class_ doc comment of "Doctrine\ORM\Mapping\Entity". If it is indeed no annotation, then you need to add @IgnoreAnnotation("Entity") to the _class_ doc comment of class Concrete\Core\File\StorageLocation\Type\Type."

And I can see that on the Add-on strip, it stated that:

Noindex Before Launch v.1.1
Add noindex into HEAD tag

My questions are - one what do I do with the error? and how do I add the code into HEAD tag?

Thanks,
A very newbie to Concrete5 (after giving up on WP)