CA-123640: clarify use of LEAFCLSC_OFFLINE

Signed-off-by: Thanos Makatos <thanos.makatos@citrix.com>
Reviewed-by: Vineeth Thampi Raveendran <vineeth.thampi@citrix.com>
Imported-by: Siddharth Vinothkumar <siddharth.vinothkumar@citrix.com>

(cherry picked from commit e005acb0588e52e0d8a8cae8d4d57da20f06be81)

GitHub: closes #116 on xapi-project/sm