oxm_fields: Add a comment
oxm_fields: Add a comment

Signed-off-by: YAMAMOTO Takashi <458bba2e4a8704776b33478100c98529b639cd9e@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <93dac1fe9c4b2a3957982200319981492ad4976e@lab.ntt.co.jp>

lzppp/mylearning,umkcdcrg01/ryu_openflow,yamt/ryu,yamt/ryu,ynkjm/ryu,jalilm/ryu,iwaseyusuke/ryu,muzixing/ryu,alyosha1879/ryu,Tesi-Luca-Davide/ryu,evanscottgray/ryu,openvapour/ryu,takahashiminoru/ryu,Zouyiran/ryu,ttsubo/ryu,OpenState-SDN/ryu,John-Lin/ryu,habibiefaried/ryu,OpenState-SDN/ryu,lagopus/ryu-lagopus-ext,zyq001/ryu,John-Lin/ryu,gareging/SDN_Framework,hisaharu/ryu,jalilm/ryu,ysywh/ryu,openvapour/ryu,TakeshiTseng/ryu,StephenKing/summerschool-2015-ryu,umkcdcrg01/ryu_openflow,haniehrajabi/ryu,fujita/ryu,elahejalalpour/ELRyu,diogommartins/ryu,sivaramakrishnansr/ryu,shinpeimuraoka/ryu,haniehrajabi/ryu,darjus-amzn/ryu,zangree/ryu,umkcdcrg01/ryu_openflow,gopchandani/ryu,Tejas-Subramanya/RYU_MEC,fujita/ryu,jazzmes/ryu,ysywh/ryu,TakeshiTseng/ryu,hisaharu/ryu,ynkjm/ryu,StephenKing/ryu,castroflavio/ryu,hisaharu/ryu,jazzmes/ryu,StephenKing/ryu,ttsubo/ryu,fujita/ryu,Zouyiran/ryu,sivaramakrishnansr/ryu,StephenKing/summerschool-2015-ryu,OpenState-SDN/ryu,fkakuma/ryu,StephenKing/ryu,elahejalalpour/ELRyu,jazzmes/ryu,gareging/SDN_Framework,jalilm/ryu,osrg/ryu,jalilm/ryu,hisaharu/ryu,haniehrajabi/ryu,Tesi-Luca-Davide/ryu,sivaramakrishnansr/ryu,elahejalalpour/ELRyu,lzppp/mylearning,muzixing/ryu,lzppp/mylearning,gareging/SDN_Framework,iwaseyusuke/ryu,gareging/SDN_Framework,TakeshiTseng/ryu,haniehrajabi/ryu,jkoelker/ryu,alanquillin/ryu,diogommartins/ryu,lsqtongxin/ryu,ysywh/ryu,StephenKing/summerschool-2015-ryu,shinpeimuraoka/ryu,zyq001/ryu,John-Lin/ryu,lagopus/ryu-lagopus-ext,zyq001/ryu,yamt/ryu,openvapour/ryu,darjus-amzn/ryu,StephenKing/ryu,ynkjm/ryu,yamt/ryu,pichuang/ryu,alyosha1879/ryu,muzixing/ryu,lsqtongxin/ryu,umkcdcrg01/ryu_openflow,diogommartins/ryu,darjus-amzn/ryu,lagopus/ryu-lagopus-ext,fujita/ryu,osrg/ryu,ttsubo/ryu,zangree/ryu,elahejalalpour/ELRyu,muzixing/ryu,openvapour/ryu,lagopus/ryu-lagopus-ext,habibiefaried/ryu,osrg/ryu,fujita/ryu,TakeshiTseng/ryu,fkakuma/ryu,evanscottgray/ryu,jalilm/ryu,alyosha1879/ryu,fkakuma/ryu,zyq001/ryu,diogommartins/ryu,Tejas-Subramanya/RYU_MEC,StephenKing/ryu,Zouyiran/ryu,OpenState-SDN/ryu,OpenState-SDN/ryu,alanquillin/ryu,gopchandani/ryu,gareging/SDN_Framework,fkakuma/ryu,shinpeimuraoka/ryu,ysywh/ryu,Tesi-Luca-Davide/ryu,takahashiminoru/ryu,shinpeimuraoka/ryu,lsqtongxin/ryu,Zouyiran/ryu,StephenKing/summerschool-2015-ryu,sivaramakrishnansr/ryu,Tesi-Luca-Davide/ryu,hisaharu/ryu,StephenKing/summerschool-2015-ryu,ttsubo/ryu,habibiefaried/ryu,osrg/ryu,yamt/ryu,habibiefaried/ryu,haniehrajabi/ryu,fkakuma/ryu,gopchandani/ryu,evanscottgray/ryu,elahejalalpour/ELRyu,Tesi-Luca-Davide/ryu,darjus-amzn/ryu,muzixing/ryu,ynkjm/ryu,gopchandani/ryu,ynkjm/ryu,Tejas-Subramanya/RYU_MEC,openvapour/ryu,Zouyiran/ryu,diogommartins/ryu,zyq001/ryu,jkoelker/ryu,iwaseyusuke/ryu,zangree/ryu,lsqtongxin/ryu,lzppp/mylearning,zangree/ryu,jkoelker/ryu,castroflavio/ryu,alanquillin/ryu,iwaseyusuke/ryu,Tejas-Subramanya/RYU_MEC,pichuang/ryu,ysywh/ryu,takahashiminoru/ryu,castroflavio/ryu,Tejas-Subramanya/RYU_MEC,sivaramakrishnansr/ryu,alyosha1879/ryu,umkcdcrg01/ryu_openflow,iwaseyusuke/ryu,pichuang/ryu,takahashiminoru/ryu,gopchandani/ryu,alanquillin/ryu,ttsubo/ryu,pichuang/ryu,John-Lin/ryu,zangree/ryu,John-Lin/ryu,darjus-amzn/ryu,lsqtongxin/ryu,osrg/ryu,habibiefaried/ryu,lagopus/ryu-lagopus-ext,pichuang/ryu,alanquillin/ryu,takahashiminoru/ryu,TakeshiTseng/ryu,shinpeimuraoka/ryu,lzppp/mylearning