github: Add a note regarding vulnerability reports to issue template

Also updated the version numbers in the template.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -6,15 +6,19 @@ type: Bug
 ---
 
 <!--
-IMPORTANT: Please use the [discussion forum](https://github.com/strongswan/strongswan/discussions)
+IMPORTANT:
+If this is a vulnerability report, please email security@strongswan.org instead.
+This is publicly viewable and not appropriate for vulnerability reports.
+
+Please use the [discussion forum](https://github.com/strongswan/strongswan/discussions)
 for questions and configuration problems etc., only report actual bugs here.
 Your issue will otherwise be closed immediately.
 -->
 
 **System (please complete the following information):**
- - OS: [e.g. Ubuntu 20.04]
+ - OS: [e.g. Ubuntu 26.04]
- - Kernel version (if applicable): [e.g. 5.10]
+ - Kernel version (if applicable): [e.g. 7.0]
- - strongSwan version(s): [e.g. 5.9.2]
+ - strongSwan version(s): [e.g. 6.0.6]
  - Tested/confirmed with the latest version: [yes/no]
 
 **Describe the bug**