Issue Templates: Show a "Discussions" link for questions (#1152)

Instead of a fake issue template, show a Discussions link.

Author: abhinav

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,4 @@
+contact_links:
+  - name: Questions
+    about: Please use our Discussions page
+    url: https://github.com/uber-go/zap/discussions