Add developer guidelines to ads/README.md (#5129)
Add developer guidelines to ads/README.md (#5129)


pietergreyling/amphtml,DarXector/amphtml,arealit/amphtml,prateekbh/amphtml,keithwrightbos/amphtml,burtcorp/amphtml,jridgewell/amphtml,voyagegroup/amphtml,fullspeed-sp/amphtml,jmadler/amphtml,sklobovskaya/amphtml,gumgum/amphtml,powdercloud/amphtml,sharethrough/amphtml,kmh287/amphtml,Gregable/amphtml,alanorozco/amphtml,powdercloud/amphtml,sebastianbenz/amphtml,jlucero-contentad/amphtml,media-net/amphtml,chaveznvg/amphtml,rlugojr/amphtml,adiant/amphtml,kixer-com/amphtml,lannka/amphtml,lannka/amphtml,zhangsu/amphtml,tlong2/amphtml,kixer-com/amphtml,rajkumarsrk/amphtml,pietergreyling/amphtml,spotxchange/amphtml,cvializ/amphtml,triplelift/amphtml,honeybadgerdontcare/amphtml,tlong2/amphtml,zhouyx/amphtml,rlugojr/amphtml,engtat/amphtml,kmh287/amphtml,BrightcoveOS/amphtml,clawr/amphtml,vmarteev/amphtml,adtechnology/amphtml,pedjoni8/amphtml,erwinmombay/amphtml,jpettitt/amphtml,keithwrightbos/amphtml,BrightcoveOS/amphtml,media-net/amphtml,engtat/amphtml,kmh287/amphtml,tdrl/amphtml,Adtoma/amphtml,aghassemi/amphtml,jridgewell/amphtml,DarXector/amphtml,interspacejp/amphtml,DistroScale/amphtml,interspacejp/amphtml,lzanol/amphtml,triplelift/amphtml,engtat/amphtml,rsimha-amp/amphtml,techhtml/amphtml,shawnbuso/amphtml,mhc-gh/amphtml,sharethrough/amphtml,adtechnology/amphtml,honeybadgerdontcare/amphtml,zhucl/amphtml,sortable/amphtml,adtechnology/amphtml,sebastianbenz/amphtml,mhc-gh/amphtml,nexxtv/amphtml,zhucl/amphtml,sklobovskaya/amphtml,gumgum/amphtml,fullspeed-sp/amphtml,avimehta/amphtml,erwinmombay/amphtml,alanorozco/amphtml,cory-work/amphtml,cory-work/amphtml,luciancrasovan/amphtml,rajkumarsrk/amphtml,burtcorp/amphtml,ampproject/amphtml,taboola/amphtml,donttrustthisbot/amphtml,Lith/amphtml,pietergreyling/amphtml,sharethrough/amphtml,gumgum/amphtml,tdrl/amphtml,Adtoma/amphtml,DarXector/amphtml,dotandads/amphtml,zhouyx/amphtml,camelburrito/amphtml,bpaduch/amphtml,devjsun/amphtml,vmarteev/amphtml,lannka/amphtml,gumgum/amphtml,kixer-com/amphtml,ericlindley-g/amphtml,jridgewell/amphtml,keithwrightbos/amphtml,burtcorp/amphtml,pedjoni8/amphtml,danielrozenberg/amphtml,sortable/amphtml,yandex-pcode/amphtml,avimehta/amphtml,alanorozco/amphtml,zhouyx/amphtml,honeybadgerdontcare/amphtml,bpaduch/amphtml,src-code/amphtml,jmadler/amphtml,zhangsu/amphtml,mhc-gh/amphtml,spotxchange/amphtml,vmarteev/amphtml,koshka/amphtml,techhtml/amphtml,laterpay/amphtml,dvoytenko/amphtml,danielrozenberg/amphtml,mlb7687/amphtml,nexxtv/amphtml,yandex-pcode/amphtml,nexxtv/amphtml,prateekbh/amphtml,vmarteev/amphtml,avimehta/amphtml,sklobovskaya/amphtml,fullspeed-sp/amphtml,adup-tech/amphtml,pietergreyling/amphtml,donttrustthisbot/amphtml,zhangsu/amphtml,ruturajv-media-net/amphtml,pedjoni8/amphtml,dotandads/amphtml,voyagegroup/amphtml,taboola/amphtml,sriramkrish85/amphtml,jmadler/amphtml,adup-tech/amphtml,kixer-com/amphtml,engtat/amphtml,devjsun/amphtml,mlb7687/amphtml,luciancrasovan/amphtml,chaveznvg/amphtml,jridgewell/amphtml,dotandads/amphtml,media-net/amphtml,aghassemi/amphtml,DAC-f1h-dev/amphtml,sortable/amphtml,ecoron/amphtml,ampproject/amphtml,lzanol/amphtml,ecoron/amphtml,kixer-com/amphtml,comScore/amphtml,Adtoma/amphtml,camelburrito/amphtml,techhtml/amphtml,shawnbuso/amphtml,bpaduch/amphtml,comScore/amphtml,jlucero-contentad/amphtml,sriramkrish85/amphtml,prateekbh/amphtml,JuliusThms/amphtml,yieldbot/amphtml,donttrustthisbot/amphtml,avimehta/amphtml,voyagegroup/amphtml,burtcorp/amphtml,kamtschatka/amphtml,erwinmombay/amphtml,yieldbot/amphtml,chaveznvg/amphtml,ampproject/amphtml,DarXector/amphtml,Mixpo/amphtml,DistroScale/amphtml,voyagegroup/amphtml,kamtschatka/amphtml,keithwrightbos/amphtml,Mixpo/amphtml,jridgewell/amphtml,ADITION/amphtml,lzanol/amphtml,rifler/amphtml,rajkumarsrk/amphtml,jpettitt/amphtml,interspacejp/amphtml,koshka/amphtml,zhouyx/amphtml,koshka/amphtml,triplelift/amphtml,rifler/amphtml,keithwrightbos/amphtml,lannka/amphtml,prateekbh/amphtml,Gregable/amphtml,bpaduch/amphtml,yandex-pcode/amphtml,donttrustthisbot/amphtml,yieldmo/amphtml,smartadserver/amphtml,src-code/amphtml,jdelhommeau/amphtml,rsimha-amp/amphtml,danielrozenberg/amphtml,bpaduch/amphtml,zhangsu/amphtml,Mixpo/amphtml,jdelhommeau/amphtml,zhangsu/amphtml,arealit/amphtml,DistroScale/amphtml,cory-work/amphtml,BenDz/amphtml,spotxchange/amphtml,taboola/amphtml,cvializ/amphtml,interspacejp/amphtml,avimehta/amphtml,donttrustthisbot/amphtml,pietergreyling/amphtml,voyagegroup/amphtml,danielrozenberg/amphtml,smartadserver/amphtml,zhucl/amphtml,Adtoma/amphtml,ruturajv-media-net/amphtml,mhc-gh/amphtml,adtechnology/amphtml,bpaduch/amphtml,koshka/amphtml,rifler/amphtml,pedjoni8/amphtml,vmarteev/amphtml,cvializ/amphtml,taboola/amphtml,kamtschatka/amphtml,BenDz/amphtml,adup-tech/amphtml,rsimha-amp/amphtml,aghassemi/amphtml,cory-work/amphtml,BenDz/amphtml,rlugojr/amphtml,mlb7687/amphtml,rajkumarsrk/amphtml,nexxtv/amphtml,jpettitt/amphtml,ecoron/amphtml,zhangsu/amphtml,chaveznvg/amphtml,BrightcoveOS/amphtml,jdelhommeau/amphtml,interspacejp/amphtml,jridgewell/amphtml,sharethrough/amphtml,DAC-f1h-dev/amphtml,laterpay/amphtml,kamtschatka/amphtml,fullspeed-sp/amphtml,danielrozenberg/amphtml,rlugojr/amphtml,shawnbuso/amphtml,honeybadgerdontcare/amphtml,powdercloud/amphtml,burtcorp/amphtml,powdercloud/amphtml,sharethrough/amphtml,koshka/amphtml,Adtoma/amphtml,smartadserver/amphtml,pedjoni8/amphtml,zhucl/amphtml,dotandads/amphtml,jpettitt/amphtml,chaveznvg/amphtml,laterpay/amphtml,Mixpo/amphtml,bpaduch/amphtml,sriramkrish85/amphtml,devjsun/amphtml,DistroScale/amphtml,smartadserver/amphtml,luciancrasovan/amphtml,erwinmombay/amphtml,DistroScale/amphtml,Gregable/amphtml,engtat/amphtml,jlucero-contentad/amphtml,shawnbuso/amphtml,techhtml/amphtml,luciancrasovan/amphtml,camelburrito/amphtml,sharethrough/amphtml,jmadler/amphtml,Lith/amphtml,zhucl/amphtml,sebastianbenz/amphtml,tdrl/amphtml,rsimha-amp/amphtml,lannka/amphtml,pietergreyling/amphtml,src-code/amphtml,tdrl/amphtml,yandex-pcode/amphtml,laterpay/amphtml,yieldmo/amphtml,engtat/amphtml,adup-tech/amphtml,vmarteev/amphtml,adiant/amphtml,triplelift/amphtml,rifler/amphtml,ericlindley-g/amphtml,wjfang/amphtml,widespace-os/amphtml,alanorozco/amphtml,Mobusi-ads/amphtml,JuliusThms/amphtml,yieldmo/amphtml,yandex-pcode/amphtml,nexxtv/amphtml,aghassemi/amphtml,adiant/amphtml,adiant/amphtml,arealit/amphtml,Mixpo/amphtml,honeybadgerdontcare/amphtml,widespace-os/amphtml,taboola/amphtml,smartadserver/amphtml,zhouyx/amphtml,powdercloud/amphtml,BenDz/amphtml,jmadler/amphtml,wjfang/amphtml,widespace-os/amphtml,Gregable/amphtml,adiant/amphtml,zhouyx/amphtml,media-net/amphtml,triplelift/amphtml,lannka/amphtml,yieldmo/amphtml,zhucl/amphtml,dotandads/amphtml,prateekbh/amphtml,rlugojr/amphtml,ampproject/amphtml,cory-work/amphtml,jlucero-contentad/amphtml,ampproject/amphtml,spotxchange/amphtml,src-code/amphtml,zhucl/amphtml,vmarteev/amphtml,techhtml/amphtml,kixer-com/amphtml,voyagegroup/amphtml,Mobusi-ads/amphtml,mhc-gh/amphtml,devjsun/amphtml,src-code/amphtml,BenDz/amphtml,techhtml/amphtml,widespace-os/amphtml,camelburrito/amphtml,ADITION/amphtml,keithwrightbos/amphtml,lzanol/amphtml,DAC-f1h-dev/amphtml,Mixpo/amphtml,comScore/amphtml,arealit/amphtml,alanorozco/amphtml,tlong2/amphtml,gumgum/amphtml,BrightcoveOS/amphtml,dvoytenko/amphtml,yieldmo/amphtml,dotandads/amphtml,sriramkrish85/amphtml,wjfang/amphtml,nexxtv/amphtml,dvoytenko/amphtml,cvializ/amphtml,prateekbh/amphtml,lannka/amphtml,jmadler/amphtml,ericlindley-g/amphtml,clawr/amphtml,ADITION/amphtml,ADITION/amphtml,adup-tech/amphtml,engtat/amphtml,powdercloud/amphtml,clawr/amphtml,rlugojr/amphtml,DAC-f1h-dev/amphtml,DarXector/amphtml,dvoytenko/amphtml,JuliusThms/amphtml,Mobusi-ads/amphtml,rifler/amphtml,tlong2/amphtml,jdelhommeau/amphtml,voyagegroup/amphtml,laterpay/amphtml,BrightcoveOS/amphtml,rajkumarsrk/amphtml,src-code/amphtml,sortable/amphtml,honeybadgerdontcare/amphtml,JuliusThms/amphtml,taboola/amphtml,wjfang/amphtml,mhc-gh/amphtml,erwinmombay/amphtml,clawr/amphtml,adiant/amphtml,yandex-pcode/amphtml,tdrl/amphtml,jdelhommeau/amphtml,media-net/amphtml,cvializ/amphtml,Mobusi-ads/amphtml,alanorozco/amphtml,avimehta/amphtml,koshka/amphtml,mlb7687/amphtml,shawnbuso/amphtml,nexxtv/amphtml,mlb7687/amphtml,prateekbh/amphtml,DarXector/amphtml,honeybadgerdontcare/amphtml,keithwrightbos/amphtml,aghassemi/amphtml,Mobusi-ads/amphtml,jpettitt/amphtml,tlong2/amphtml,jridgewell/amphtml,DistroScale/amphtml,gumgum/amphtml,arealit/amphtml,pedjoni8/amphtml,kamtschatka/amphtml,smartadserver/amphtml,aghassemi/amphtml,luciancrasovan/amphtml,lzanol/amphtml,comScore/amphtml,yieldmo/amphtml,ampproject/amphtml,rajkumarsrk/amphtml,JuliusThms/amphtml,comScore/amphtml,alanorozco/amphtml,ruturajv-media-net/amphtml,JuliusThms/amphtml,kamtschatka/amphtml,widespace-os/amphtml,taboola/amphtml,yieldbot/amphtml,donttrustthisbot/amphtml,wjfang/amphtml,Gregable/amphtml,devjsun/amphtml,lzanol/amphtml,burtcorp/amphtml,ericlindley-g/amphtml,ericlindley-g/amphtml,ericlindley-g/amphtml,chaveznvg/amphtml,zhouyx/amphtml,ruturajv-media-net/amphtml,adup-tech/amphtml,kmh287/amphtml,camelburrito/amphtml,yieldbot/amphtml,sebastianbenz/amphtml,danielrozenberg/amphtml,ruturajv-media-net/amphtml,adiant/amphtml,cvializ/amphtml,ruturajv-media-net/amphtml,tdrl/amphtml,sklobovskaya/amphtml,fullspeed-sp/amphtml,cory-work/amphtml,jpettitt/amphtml,media-net/amphtml,comScore/amphtml,Adtoma/amphtml,rsimha-amp/amphtml,adtechnology/amphtml,ampproject/amphtml,devjsun/amphtml,sortable/amphtml,Lith/amphtml,Gregable/amphtml,Lith/amphtml,yandex-pcode/amphtml,jpettitt/amphtml,sriramkrish85/amphtml,media-net/amphtml,yieldbot/amphtml,clawr/amphtml,Gregable/amphtml,gumgum/amphtml,danielrozenberg/amphtml,ecoron/amphtml,dvoytenko/amphtml,luciancrasovan/amphtml,sriramkrish85/amphtml,cory-work/amphtml,wjfang/amphtml,kmh287/amphtml,Gregable/amphtml,ampproject/amphtml,shawnbuso/amphtml,jpettitt/amphtml,sklobovskaya/amphtml,adtechnology/amphtml,DAC-f1h-dev/amphtml,sebastianbenz/amphtml,mlb7687/amphtml,sklobovskaya/amphtml,camelburrito/amphtml,tlong2/amphtml,sklobovskaya/amphtml,media-net/amph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