chore: add context information to stale bot message text
@@ -17,6 +17,6 @@ exemptMilestones: true
staleLabel: stale
markComment: >
- This issue has been automatically marked as stale because it has not had
- recent activity. It will be closed if no further activity occurs. Thank you
- for your contributions.
+ This issue has been [automatically marked as stale](https://probot.github.io/apps/stale/#how-it-works)
+ because it has not had recent activity. It will be closed in 7 days if no
+ further activity occurs. Thank you for your contributions.
