Update stale issue comment to mention 6-0-stable
Update stale issue comment to mention 6-0-stable

6-0-stable is the release series that currently receives bug fixes.

yalab/rails,Vasfed/rails,lcreid/rails,kddeisz/rails,yawboakye/rails,shioyama/rails,Vasfed/rails,Vasfed/rails,yawboakye/rails,yahonda/rails,rails/rails,arunagw/rails,fabianoleittes/rails,prathamesh-sonpatki/rails,shioyama/rails,iainbeeston/rails,Edouard-chin/rails,Vasfed/rails,repinel/rails,Edouard-chin/rails,notapatch/rails,fabianoleittes/rails,joonyou/rails,betesh/rails,eileencodes/rails,eileencodes/rails,joonyou/rails,Envek/rails,bogdanvlviv/rails,joonyou/rails,MSP-Greg/rails,yalab/rails,georgeclaghorn/rails,gauravtiwari/rails,iainbeeston/rails,notapatch/rails,yhirano55/rails,esparta/rails,yawboakye/rails,BlakeWilliams/rails,shioyama/rails,kmcphillips/rails,kddeisz/rails,betesh/rails,arunagw/rails,yahonda/rails,fabianoleittes/rails,schuetzm/rails,mechanicles/rails,Stellenticket/rails,BlakeWilliams/rails,vipulnsward/rails,kmcphillips/rails,shioyama/rails,Envek/rails,jeremy/rails,bogdanvlviv/rails,prathamesh-sonpatki/rails,BlakeWilliams/rails,BlakeWilliams/rails,Edouard-chin/rails,Envek/rails,yahonda/rails,rafaelfranca/omg-rails,prathamesh-sonpatki/rails,eileencodes/rails,esparta/rails,bogdanvlviv/rails,Erol/rails,rails/rails,tjschuck/rails,Stellenticket/rails,tjschuck/rails,tjschuck/rails,EmmaB/rails-1,betesh/rails,schuetzm/rails,MSP-Greg/rails,palkan/rails,tgxworld/rails,iainbeeston/rails,kddeisz/rails,gauravtiwari/rails,Erol/rails,prathamesh-sonpatki/rails,Erol/rails,vipulnsward/rails,MSP-Greg/rails,yalab/rails,Envek/rails,Stellenticket/rails,fabianoleittes/rails,palkan/rails,Erol/rails,yawboakye/rails,schuetzm/rails,georgeclaghorn/rails,notapatch/rails,kmcphillips/rails,yhirano55/rails,jeremy/rails,repinel/rails,yahonda/rails,starknx/rails,joonyou/rails,EmmaB/rails-1,yalab/rails,lcreid/rails,betesh/rails,repinel/rails,lcreid/rails,georgeclaghorn/rails,starknx/rails,mechanicles/rails,Stellenticket/rails,eileencodes/rails,vipulnsward/rails,Edouard-chin/rails,jeremy/rails,arunagw/rails,kddeisz/rails,mechanicles/rails,lcreid/rails,georgeclaghorn/rails,rafaelfranca/omg-rails,palkan/rails,repinel/rails,schuetzm/rails,rails/rails,iainbeeston/rails,yhirano55/rails,tgxworld/rails,bogdanvlviv/rails,gauravtiwari/rails,kmcphillips/rails,esparta/rails,rails/rails,mechanicles/rails,rafaelfranca/omg-rails,notapatch/rails,EmmaB/rails-1,tgxworld/rails,jeremy/rails,starknx/rails,tgxworld/rails,vipulnsward/rails,MSP-Greg/rails,esparta/rails,yhirano55/rails,tjschuck/rails,palkan/rails,arunagw/rails