Fixed the minimum requirement of the library
Fixed the minimum requirement of the library

The library has been tagged as alpha2, not as beta1
Soullivaneuh/KnpMenuBundle,benji07/KnpMenuBundle,Soullivaneuh/KnpMenuBundle,javiereguiluz/KnpMenuBundle,stof/KnpMenuBundle,Nek-/KnpMenuBundle,KnpLabs/KnpMenuBundle,piotrantosik/KnpMenuBundle,bocharsky-bw/KnpMenuBundle