add dates for the next releases in release_manager_guide.pod
add dates for the next releases in release_manager_guide.pod

Util for 6.0.0 (to be verified), rurban for 6.1.0

FROGGS/parrot,FROGGS/parrot,youprofit/parrot,youprofit/parrot,parrot/parrot,tkob/parrot,tkob/parrot,tkob/parrot,youprofit/parrot,parrot/parrot,FROGGS/parrot,youprofit/parrot,parrot/parrot,FROGGS/parrot,tkob/parrot,tkob/parrot,tkob/parrot,youprofit/parrot,tkob/parrot,FROGGS/parrot,youprofit/parrot,tkob/parrot,youprofit/parrot,youprofit/parrot,parrot/parrot,parrot/parrot,FROGGS/parrot,FROGGS/parrot,FROGGS/parrot