engine: Missing language docs message

- The display 'language' was not translated into the locale of the
  message. This caused for instance Japanese to be in English in the
  Japanese translated message.

Change-Id: I1d9348e6e9782858edc2ecfafea0d5fd740cb4fc
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1132733
Signed-off-by: Alexander Wels <awels@redhat.com>