Added precisions about the child customization
Added precisions about the child customization

Nek-/KnpMenuBundle,Soullivaneuh/KnpMenuBundle,piotrantosik/KnpMenuBundle,benji07/KnpMenuBundle,craue/MenuBundle,stof/KnpMenuBundle,KnpLabs/KnpMenuBundle,WouterJ/KnpMenuBundle,javiereguiluz/KnpMenuBundle,bocharsky-bw/KnpMenuBundle,Soullivaneuh/KnpMenuBundle