LU-6239 doc: include missing lnetctl.8

LU-6239 doc: include missing lnetctl.8

Doing a man lnetctl currently doesn't work on system
with lustre installed. This is due to lnetctl.8 does
not get included in generated rpms. This simple fix
ensure lnetctl.8 is included in the rpms.

Change-Id: I72e2ef2841f5936e1d0def538c239ee2da32d7c3
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Reviewed-on: http://review.whamcloud.com/13749
Reviewed-by: Amir Shehata <amir.shehata@intel.com>
Tested-by: Jenkins
Reviewed-by: Isaac Huang <he.huang@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>