Update ose-elk-01-logging.md

The 'multi' option was added in 2.1.7 and allows the cartridge logs to be both sent to syslog and remain in-gear. Developers will prefer having local access to their logs in gear (e.g. rhc tail).
Merge pull request #1 from edseymour/patch-1

Change node logging to multi for both (gear) local and syslog logs.