docs: configure issue templates

Author: drnecrotix

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,5 @@
+blank_issues_enabled: false
+contact_links:
+  - name: Security vulnerability
+    url: https://github.com/drnecrotix/WP-SSO/security/policy
+    about: Report sensitive authentication or credential issues according to the security policy.