Update stale issue comment to mention 7-0-stable
Update stale issue comment to mention 7-0-stable

7-0-stable is the release series that currently receives bug fixes.

kmcphillips/rails,kmcphillips/rails,yahonda/rails,yawboakye/rails,esparta/rails,yawboakye/rails,yahonda/rails,georgeclaghorn/rails,georgeclaghorn/rails,BlakeWilliams/rails,rails/rails,MSP-Greg/rails,BlakeWilliams/rails,yahonda/rails,Edouard-chin/rails,Erol/rails,BlakeWilliams/rails,kddeisz/rails,yawboakye/rails,rails/rails,rails/rails,BlakeWilliams/rails,kmcphillips/rails,yahonda/rails,yawboakye/rails,esparta/rails,Erol/rails,Edouard-chin/rails,Edouard-chin/rails,rails/rails,MSP-Greg/rails,MSP-Greg/rails,esparta/rails,esparta/rails,kddeisz/rails,Erol/rails,georgeclaghorn/rails,MSP-Greg/rails,kmcphillips/rails,kddeisz/rails,georgeclaghorn/rails,Edouard-chin/rails,Erol/rails,kddeisz/rails