Add "License" section to CONTRIBUTING.md
Add "License" section to CONTRIBUTING.md

stefanbuettner/pcl,pkuhto/pcl,shangwuhencc/pcl,chatchavan/pcl,ResByte/pcl,ipa-rmb/pcl,damienjadeduff/pcl,zavataafnan/pcl-truck,fskuka/pcl,closerbibi/pcl,soulsheng/pcl,mikhail-matrosov/pcl,nikste/pcl,DaikiMaekawa/pcl,LZRS/pcl,shivmalhotra/pcl,fanxiaochen/mypcltest,zhangxaochen/pcl,mikhail-matrosov/pcl,DaikiMaekawa/pcl,damienjadeduff/pcl,closerbibi/pcl,Tabjones/pcl,shivmalhotra/pcl,shangwuhencc/pcl,KevenRing/pcl,jakobwilm/pcl,damienjadeduff/pcl,mikhail-matrosov/pcl,chenxingzhe/pcl,wgapl/pcl,lebronzhang/pcl,jeppewalther/kinfu_segmentation,raydtang/pcl,locnx1984/pcl,fskuka/pcl,kanster/pcl,fskuka/pcl,RufaelDev/pcc-mp3dg,KevenRing/vlp,jeppewalther/kinfu_segmentation,cascheberg/pcl,kanster/pcl,3dtof/pcl,msalvato/pcl_kinfu_highres,fskuka/pcl,KevenRing/pcl,shyamalschandra/pcl,RufaelDev/pcc-mp3dg,msalvato/pcl_kinfu_highres,mschoeler/pcl,KevenRing/vlp,kanster/pcl,simonleonard/pcl,cascheberg/pcl,v4hn/pcl,the-glu/pcl,Tabjones/pcl,starius/pcl,starius/pcl,LZRS/pcl,zavataafnan/pcl-truck,MMiknis/pcl,zhangxaochen/pcl,the-glu/pcl,stfuchs/pcl,lebronzhang/pcl,chatchavan/pcl,mschoeler/pcl,KevenRing/vlp,drmateo/pcl,mschoeler/pcl,fskuka/pcl,pkuhto/pcl,wgapl/pcl,KevenRing/vlp,msalvato/pcl_kinfu_highres,MMiknis/pcl,shangwuhencc/pcl,ResByte/pcl,srbhprajapati/pcl,lydhr/pcl,lydhr/pcl,sbec/pcl,damienjadeduff/pcl,stefanbuettner/pcl,msalvato/pcl_kinfu_highres,raydtang/pcl,chatchavan/pcl,zavataafnan/pcl-truck,chenxingzhe/pcl,Tabjones/pcl,shyamalschandra/pcl,v4hn/pcl,srbhprajapati/pcl,closerbibi/pcl,KevenRing/pcl,KevenRing/pcl,pkuhto/pcl,LZRS/pcl,srbhprajapati/pcl,3dtof/pcl,zavataafnan/pcl-truck,krips89/pcl_newfeatures,jakobwilm/pcl,zhangxaochen/pcl,MMiknis/pcl,shyamalschandra/pcl,chenxingzhe/pcl,pkuhto/pcl,wgapl/pcl,KevenRing/pcl,zhangxaochen/pcl,lydhr/pcl,mikhail-matrosov/pcl,the-glu/pcl,starius/pcl,Tabjones/pcl,3dtof/pcl,fanxiaochen/mypcltest,simonleonard/pcl,soulsheng/pcl,KevenRing/vlp,ipa-rmb/pcl,nikste/pcl,LZRS/pcl,mikhail-matrosov/pcl,lydhr/pcl,LZRS/pcl,RufaelDev/pcc-mp3dg,drmateo/pcl,krips89/pcl_newfeatures,ResByte/pcl,simonleonard/pcl,DaikiMaekawa/pcl,DaikiMaekawa/pcl,srbhprajapati/pcl,soulsheng/pcl,fanxiaochen/mypcltest,RufaelDev/pcc-mp3dg,kanster/pcl,stfuchs/pcl,3dtof/pcl,msalvato/pcl_kinfu_highres,ResByte/pcl,krips89/pcl_newfeatures,soulsheng/pcl,kanster/pcl,chenxingzhe/pcl,ResByte/pcl,cascheberg/pcl,RufaelDev/pcc-mp3dg,stfuchs/pcl,srbhprajapati/pcl,fanxiaochen/mypcltest,stefanbuettner/pcl,raydtang/pcl,DaikiMaekawa/pcl,simonleonard/pcl,krips89/pcl_newfeatures,sbec/pcl,jeppewalther/kinfu_segmentation,drmateo/pcl,sbec/pcl,stefanbuettner/pcl,closerbibi/pcl,ipa-rmb/pcl,closerbibi/pcl,jeppewalther/kinfu_segmentation,cascheberg/pcl,krips89/pcl_newfeatures,zavataafnan/pcl-truck,raydtang/pcl,simonleonard/pcl,shivmalhotra/pcl,Tabjones/pcl,lydhr/pcl,chatchavan/pcl,nikste/pcl,wgapl/pcl,locnx1984/pcl,ipa-rmb/pcl,soulsheng/pcl,pkuhto/pcl,shivmalhotra/pcl,nikste/pcl,lebronzhang/pcl,cascheberg/pcl,stefanbuettner/pcl,locnx1984/pcl,jakobwilm/pcl,jakobwilm/pcl,shyamalschandra/pcl,drmateo/pcl,nikste/pcl,stfuchs/pcl,locnx1984/pcl,sbec/pcl,lebronzhang/pcl,stfuchs/pcl,shangwuhencc/pcl,v4hn/pcl,3dtof/pcl,fanxiaochen/mypcltest,raydtang/pcl,ipa-rmb/pcl,v4hn/pcl,locnx1984/pcl,jakobwilm/pcl,mschoeler/pcl,zhangxaochen/pcl,starius/pcl,chenxingzhe/pcl,v4hn/pcl,the-glu/pcl,the-glu/pcl,shangwuhencc/pcl,wgapl/pcl,shivmalhotra/pcl,mschoeler/pcl,MMiknis/pcl,damienjadeduff/pcl,lebronzhang/pcl,starius/pcl,sbec/pcl,MMiknis/pcl,jeppewalther/kinfu_segmentation,shyamalschandra/pcl,drmateo/pcl