Upgrade Doc for 8.14: Missing new elasticsearch requirement

Summary

In GitLab EE 8.14, the requirement for Elasticsearch was changed to 2.4.x with MR !896 (merged) .

But there seems to be mention of this either in the release blog post or the upgrade documentation for GitLab EE, 8.13 ➡ 8.14.

Steps to reproduce

Upgrade a GitLab-EE installation with Elasticsearch 2.3.x, from 8.13 to 8.14 and run the rake-task "check". The check task will complain that the installed version of Elasticsearch is too old.

Possible fixes

• Adjust the blog post to mention the new requirement
• Adjust the 8.13 ➡ 8.14 upgrade document for GitLab EE

Questions

• Which documentation should Omnibus users consult when upgrading to get informed about changes like this?