docs(contributing): explain how to report a vulnerability

CONTRIBUTING.rst

@@ -6,14 +6,23 @@ As an open source project, Discuss Data welcomes contributions of many forms.
 
 Examples of contributions include:
 
+* Vulnerability reports
 * Code patches
 * Documentation improvements
 * `Bug reports`_ and patch reviews
 * Feature requests
 * Merge requests
 
-Discuss Data uses pre-commit hooks to ensure the compliance of contributions with our coding standards.
-::
+Vulnerability reports
+=====================
+
+If you need to report a vulnerability, please send an E-Mail to gitlab+discuss-data-discuss-data-9289-issue-@gwdg.de
+Be aware that, by default, your E-Mail will be sent unencrypted.
+
+Code patches
+============
+
+Discuss Data uses pre-commit hooks to ensure the compliance of contributions with our coding standards.::
 
   pre-commit install