It would be nice to get the documentation in several language though! :-)
As mentioned by Vero, we have Jira documentation available for latest and older versions in English, in both online and downloadable PDF formats. I think what you are specifically looking for is Jira Service Desk 3.9 documentation, which can be found here: https://confluence.atlassian.com/servicedeskserver039/jira-service-desk-server-3-9-documentation-942845829.html