Update docs/upgrade.rst
Update docs/upgrade.rst
nicolascine/mongoengine,muhammad-ammar/mongoengine,RussellLuo/mongoengine,yarneo/mongoengine,touilleMan/mongoengine,gmacon/mongoengine,eli-b/mongoengine,larsbutler/mongoengine,losintikfos/mongoengine,ConsumerPhysics/mongoengine,elephanter/mongoengine,jimmyshen/mongoengine,Davidrjx/mongoengine,gavincabbage/mongoengine,DavidBord/mongoengine,khallaghi/mongoengine,nathanial/mongoengine,MakerReduxCorp/mongoengine,closeio/mongoengine,noirbizarre/mongoengine,9nix00/mongoengine,Davidrjx/mongoengine,Catstyle/mongoengine,blaggacao/mongoengine,starsirius/mongoengine,ms5/mongoengine,ProgressivePlanning/mongoengine,iandd0824/mongoengine,reallistic/mongoengine,MRigal/mongoengine,sourcelair/mongoengine,MakerReduxCorp/mongoengine,cogniteev/mongoengine,prijindal/mongoengine,Multiposting/mongoengine,WingGao/mongoengine,MongoEngine/mongoengine,cogniteev/mongoengine