Add contact links for reporting a vulnerability and for support

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/.github/ISSUE_TEMPLATE/config.yml b/.github/ISSUE_TEMPLATE/config.yml
index 3ba13e0..63076f4 100644
--- a/.github/ISSUE_TEMPLATE/config.yml
+++ b/.github/ISSUE_TEMPLATE/config.yml
@@ -1 +1,8 @@
 blank_issues_enabled: false
+contact_links:
+    - name: Mbed TLS security team
+      url: mailto:mbed-tls-security@lists.trustedfirmware.org
+      about: Report a security vulnerability.
+    - name: Mbed TLS mailing list
+      url: https://lists.trustedfirmware.org/mailman/listinfo/mbed-tls
+      about: Mbed TLS community support and general discussion.