Add back the security section from v1

Author: pascalandy

docs/content/contributing/submitting-security-issues.md

@@ -0,0 +1,16 @@
+# Security
+
+## Security Advisories
+
+We strongly advise you to join our mailing list to be aware of the latest announcements from our security team.
+You can subscribe sending a mail to [email protected] or on [the online viewer](https://groups.google.com/a/traefik.io/forum/#!forum/security).
+
+## CVE
+
+Reported vulnerabilities can be found on 
+[cve.mitre.org](https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=traefik).
+
+## Report a Vulnerability
+
+We want to keep Traefik safe for everyone.
+If you've discovered a security vulnerability in Traefik, we appreciate your help in disclosing it to us in a responsible manner, using [this form](https://security.traefik.io).

docs/mkdocs.yml

@@ -157,6 +157,7 @@ nav:
       - 'Thank You!': 'contributing/thank-you.md'
       - 'Submitting Issues': 'contributing/submitting-issues.md'
       - 'Submitting PRs': 'contributing/submitting-pull-requests.md'
+      - 'Security': 'contributing/submitting-security-issues.md'
       - 'Building and Testing': 'contributing/building-testing.md'
       - 'Documentation': 'contributing/documentation.md'
       - 'Data Collection': 'contributing/data-collection.md'