Add configuration for "Lock" app (#638)

To prevent people from writing related and unrelated things to already closed issues. As a maitainer, that kind of situation only makes it harder to effectively provide user support. Please create another issue with concrete description of "your issue" and the reproduction steps, rather than commenting "me too" on unrelated issues!

.github/lock.yml

@@ -0,0 +1,25 @@
+# Configuration for Lock Threads
+# Repo: https://github.com/dessant/lock-threads-app
+# App: https://github.com/apps/lock
+
+# Number of days of inactivity before a closed issue or pull request is locked
+daysUntilLock: 7
+
+# Skip issues and pull requests created before a given timestamp. Timestamp must
+# follow ISO 8601 (`YYYY-MM-DD`). Set to `false` to disable
+skipCreatedBefore: false
+
+# Issues and pull requests with these labels will be ignored. Set to `[]` to disable
+exemptLabels: []
+
+# Label to add before locking, such as `outdated`. Set to `false` to disable
+lockLabel: false
+
+# Comment to post before locking. Set to `false` to disable
+lockComment: >
+  This thread has been automatically locked since there has not been
+  any recent activity after it was closed. Please open a new issue for
+  related bugs.
+
+# Assign `resolved` as the reason for locking. Set to `false` to disable
+setLockReason: true