add default probot/stale.yml (#197)

see #196

the only change I have made is adding the `good first patch` label to
the exemptions

.github/stale.yml

@@ -0,0 +1,22 @@
+# Configuration for probot-stale - https://github.com/probot/stale
+
+# Number of days of inactivity before an Issue or Pull Request becomes stale
+daysUntilStale: 60
+# Number of days of inactivity before a stale Issue or Pull Request is closed
+daysUntilClose: 7
+# Issues or Pull Requests with these labels will never be considered stale
+exemptLabels:
+  - pinned
+  - security
+  - good first patch
+# Label to use when marking as stale
+staleLabel: wontfix
+# 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 contributions.
+# Comment to post when closing a stale Issue or Pull Request. Set to `false` to disable
+closeComment: false
+# Limit to only `issues` or `pulls`
+# only: issues