Merge branch 'security-release' into 'master'

Improve security release documentation

I think the MailChimp step is not needed anymore because we automated it.

See merge request !1271

doc/release/security.md

@@ -20,7 +20,6 @@ Please report suspected security vulnerabilities in private to <support@gitlab.c
 1. Create feature branches for the blog post on GitLab.com and link them from the code branch
 1. Merge and publish the blog posts
 1. Send tweets about the release from `@gitlabhq`
-1. Send out an email to the 'GitLab Newsletter' mailing list on MailChimp (or the 'Subscribers' list if the security fix is for EE only)
 1. Send out an email to [the community google mailing list](https://groups.google.com/forum/#!forum/gitlabhq)
 1. Post a signed copy of our complete announcement to [oss-security](http://www.openwall.com/lists/oss-security/) and request a CVE number
 1. Add the security researcher to the [Security Researcher Acknowledgments list](http://about.gitlab.com/vulnerability-acknowledgements/)