Add a few external links to the advanced guides
Add a few external links to the advanced guides

stuart-thackray/nitrogen_core,choptastic/nitrogen_core,stuart-thackray/nitrogen_core,nitrogen/nitrogen_core,nitrogen/nitrogen_core,SovereignPrime/nitrogen_core,nitrogen/nitrogen_core,nitrogen/nitrogen_core,SovereignPrime/nitrogen_core,choptastic/nitrogen_core,stuart-thackray/nitrogen_core,choptastic/nitrogen_core,SovereignPrime/nitrogen_core