housekeeping add configuration for Lock Threads bot (via #5437)

* Create lock.yml

* add trace label to locked issues

.github/lock.yml

@@ -0,0 +1,14 @@
+daysUntilLock: 365
+skipCreatedBefore: 2017-03-29 # initial release of Swagger UI 3.0.0
+exemptLabels: []
+lockLabel: "closed-by-bot: lock"
+setLockReason: false
+only: issues
+lockComment: >
+  Locking due to inactivity.
+  
+  This is done to avoid resurrecting old issues and bumping long threads with new, possibly unrelated content.
+  
+  If you think you're experiencing something similar to what you've found here: please [open a new issue](https://github.com/swagger-api/swagger-ui/issues/new/choose), follow the template, and reference this issue in your report.
+  
+  Thanks!