use global contributing guide (#3017)

Author: davidism

.github/ISSUE_TEMPLATE/config.yml

@@ -1,8 +1,5 @@
 blank_issues_enabled: false
 contact_links:
-  - name: Security issue
-    url: https://github.com/pallets/werkzeug/security/advisories/new
-    about: Do not report security issues publicly. Create a private advisory.
   - name: Questions on Discussions
     url: https://github.com/pallets/werkzeug/discussions/
     about: Ask questions about your own code on the Discussions tab.

CODE_OF_CONDUCT.md

@@ -67,3 +67,11 @@ users, and allow the maintainers to devote more time to the projects,
 [please donate today][].
 
 [please donate today]: https://palletsprojects.com/donate
+
+## Contributing
+
+See our [detailed contributing documentation][contrib] for many ways to
+contribute, including reporting issues, requesting features, asking or answering
+questions, and making PRs.
+
+[contrib]: https://palletsprojects.com/contributing/