Improved comment about nn_chunkref
Improved comment about nn_chunkref

Signed-off-by: Martin Sustrik <4dd6061be1198639e8b05ce4fd5ead7a0dcaa0f4@250bpm.com>

ttyangf/nanomsg,featherweight/ftw-kernel-nanomsg,gdamore/mamomsg,ttyangf/nanomsg,smithed/nanomsg,zerotacg/nanomsg,potatogim/nanomsg,featherweight/ftw-kernel-nanomsg,imp/nanomsg,zerotacg/nanomsg,pakozm/nanomsg,hyperfact/nanomsg,JackDunaway/featherweight-nanomsg,simplestbest/nanomsg,linearregression/nanomsg,wirebirdlabs/featherweight-nanomsg,TTimo/nanomsg,TTimo/nanomsg,gdamore/mamomsg,cosin2008/nanomsg.NET,wfxiang08/nanomsg,modulexcite/nanomsg,modulexcite/nanomsg,imp/nanomsg,krafczyk/nanomsg,nirs/nanomsg,krafczyk/nanomsg,yan97ao/nanomsg,modulexcite/nanomsg,reqshark/nanomsg,linearregression/nanomsg,kaostao/nanomsg,cosin2008/nanomsg.NET,TTimo/nanomsg,tempbottle/nanomsg,wfxiang08/nanomsg,cosin2008/nanomsg.NET,TTimo/nanomsg,imp/nanomsg,reqshark/nanomsg,thisco-de/nanomsg,tempbottle/nanomsg,kaostao/nanomsg,pch957/nanomsg,linearregression/nanomsg,tempbottle/nanomsg,kaostao/nanomsg,yan97ao/nanomsg,kaostao/nanomsg,potatogim/nanomsg,ttyangf/nanomsg,smithed/nanomsg,thisco-de/nanomsg,smithed/nanomsg,nirs/nanomsg,hyperfact/nanomsg,pch957/nanomsg,JackDunaway/featherweight-nanomsg,ttyangf/nanomsg,simplestbest/nanomsg,pch957/nanomsg,nirs/nanomsg,krafczyk/nanomsg,wfxiang08/nanomsg,zerotacg/nanomsg,pakozm/nanomsg,reqshark/nanomsg,snikulov/nanomsg,simplestbest/nanomsg,JackDunaway/featherweight-nanomsg,smithed/nanomsg,wirebirdlabs/featherweight-nanomsg,snikulov/nanomsg,hyperfact/nanomsg,potatogim/nanomsg,gdamore/mamomsg,wirebirdlabs/featherweight-nanomsg,yan97ao/nanomsg,pakozm/nanomsg