Add details about Issue links to Vulnerability docs

doc/user/application_security/vulnerabilities/index.md

@@ -14,6 +14,7 @@ Each security vulnerability in a project's [Security Dashboard](../security_dash
 - Details of the vulnerability.
 - The status of the vulnerability within the project.
 - Available actions for the vulnerability.
+- Issues related to the vulnerability.
 
 On the vulnerability page, you can interact with the vulnerability in
 several different ways:
@@ -23,6 +24,7 @@ several different ways:
 - [Create issue](#creating-an-issue-for-a-vulnerability) - Create a new issue with the
   title and description pre-populated with information from the vulnerability report.
   By default, such issues are [confidential](../../project/issues/confidential_issues.md).
+- [Link issues](#link-issues-to-the-vulnerability) - Link existing issues to vulnerability.
 - [Solution](#automatic-remediation-for-vulnerabilities) - For some vulnerabilities,
   a solution is provided for how to fix the vulnerability.
 
@@ -50,6 +52,12 @@ project the vulnerability came from, and pre-populates it with useful informatio
 the vulnerability report. After the issue is created, GitLab redirects you to the
 issue page so you can edit, assign, or comment on the issue.
 
+## Link issues to the vulnerability
+
+You can link one or more existing issues to the vulnerability. This allows you to
+indicate that this vulnerability affects multiple issues. It also allows you to indicate
+that the resolution of one issue would resolve multiple vulnerabilities.
+
 ## Automatic remediation for vulnerabilities
 
 You can fix some vulnerabilities by applying the solution that GitLab automatically