[MNG-7905] Link to security issue reporting information

**[Arnout Engelen](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=JIRAUSER291537)** opened **[MNG-7905](https://issues.apache.org/jira/browse/MNG-7905?redirect=false)** and commented

The pom.xml already has a place where a project can describe how to report issues to the project ('issueManagement'). It might be nice to also provide a place to describe how to report security issues to the project, as that might be different from regular issues?

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No further details from [MNG-7905](https://issues.apache.org/jira/browse/MNG-7905?redirect=false)