Issue Summary
When a user attempts to access the release note page of a particular JIRA version(as of now, confirmed for versions 6.3.15 and 6.3.11) by pressing what is new button, they get a page not found error.

Steps to Reproduce

• Launch JIRA.
• Question Mark > What's New
• Users get a 404 page not found error.
  

Expected Result
JIRA takes the user to the Release note page for that version of JIRA.

Actual Result
JIRA throws the page not found/ does not exist error.

Workaround

• It seems that the pages were recently moved to a different link.
• Add a redirect from these pages to the new pages.