Add Stale bot

.github/stale.yml

@@ -0,0 +1,25 @@
+# Configuration for probot-stale - https://github.com/probot/stale
+
+# Set to true to ignore issues in a project (defaults to false)
+exemptProjects: true
+
+# Set to true to ignore issues in a milestone (defaults to false)
+exemptMilestones: true
+
+# Set to true to ignore issues with an assignee (defaults to false)
+exemptAssignees: true
+
+# Label to use when marking as stale
+staleLabel: retired
+
+# Comment to post when marking as stale. Set to `false` to disable
+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 participation and understanding.
+
+# Limit the number of actions per hour, from 1-30. Default is 30
+limitPerRun: 1
+
+# Limit to only `issues` or `pulls`
+only: issues