Reformat CONTRIBUTING.md
Reformat CONTRIBUTING.md

- some reformatting to make it better readable in smaller terminals
- adds a note that suggests validating DCO before pushing

Signed-off-by: funkyfuture <72aca1c49f1c98da99c7c6d3471c46b3b9f9e43e@riseup.net>

KevinGreene/compose,denverdino/denverdino.github.io,alexandrev/compose,brunocascio/compose,goloveychuk/compose,johnstep/docker.github.io,ChrisChinchilla/compose,au-phiware/compose,cgvarela/compose,thieman/compose,sanscontext/docker.github.io,jrabbit/compose,jeanpralo/compose,xydinesh/compose,denverdino/docker.github.io,joaofnfernandes/docker.github.io,schmunk42/compose,aduermael/docker.github.io,anweiss/docker.github.io,denverdino/docker.github.io,mindaugasrukas/compose,ZJaffee/compose,pspierce/compose,shin-/compose,mrfuxi/compose,twitherspoon/compose,danix800/docker.github.io,rillig/docker.github.io,GM-Alex/compose,bbirand/compose,denverdino/denverdino.github.io,Dakno/compose,londoncalling/docker.github.io,tangkun75/compose,nerro/compose,sdurrheimer/compose,gdevillele/docker.github.io,vlajos/compose,johnstep/docker.github.io,sebglazebrook/compose,rstacruz/compose,tangkun75/compose,joeuo/docker.github.io,JimGalasyn/docker.github.io,menglingwei/denverdino.github.io,jessekl/compose,browning/compose,jessekl/compose,alexisbellido/docker.github.io,bdwill/docker.github.io,docker/docker.github.io,ggtools/compose,swoopla/compose,Katlean/fig,anweiss/docker.github.io,thaJeztah/docker.github.io,dilgerma/compose,feelobot/compose,sanscontext/docker.github.io,gdevillele/docker.github.io,danix800/docker.github.io,mdaue/compose,RobertNorthard/compose,dockerhn/compose,ain/compose,joaofnfernandes/docker.github.io,nerro/compose,thaJeztah/docker.github.io,zhangspook/compose,jrabbit/compose,jorgeLuizChaves/compose,andrewgee/compose,nhumrich/compose,bdwill/docker.github.io,LuisBosquez/docker.github.io,rillig/docker.github.io,phiroict/docker,saada/compose,danix800/docker.github.io,talolard/compose,shin-/docker.github.io,thaJeztah/compose,prologic/compose,ralphtheninja/compose,feelobot/compose,sebglazebrook/compose,vlajos/compose,bdwill/docker.github.io,kikkomep/compose,Yelp/docker-compose,artemkaint/compose,gdevillele/docker.github.io,thaJeztah/compose,denverdino/compose,screwgoth/compose,LuisBosquez/docker.github.io,shubheksha/docker.github.io,genki/compose,johnstep/docker.github.io,cgvarela/compose,gdevillele/docker.github.io,TomasTomecek/compose,d2bit/compose,josephpage/compose,xydinesh/compose,calou/compose,bdwill/docker.github.io,dnephin/compose,gtrdotmcs/compose,jorgeLuizChaves/compose,dnephin/compose,glogiotatidis/compose,thaJeztah/docker.github.io,dopry/compose,dilgerma/compose,shubheksha/docker.github.io,alexisbellido/docker.github.io,TheDataShed/compose,dbdd4us/compose,lmesz/compose,VinceBarresi/compose,JimGalasyn/docker.github.io,qzio/compose,jgrowl/compose,jiekechoo/compose,troy0820/docker.github.io,jzwlqx/denverdino.github.io,j-fuentes/compose,dockerhn/compose,ain/compose,charleswhchan/compose,mohitsoni/compose,denverdino/denverdino.github.io,denverdino/docker.github.io,calou/compose,mosquito/docker-compose,albers/compose,MSakamaki/compose,mark-adams/compose,tpounds/compose,zhangspook/compose,ph-One/compose,hoogenm/compose,mrfuxi/compose,docker/docker.github.io,joaofnfernandes/docker.github.io,talolard/compose,shubheksha/docker.github.io,troy0820/docker.github.io,joeuo/docker.github.io,shubheksha/docker.github.io,rillig/docker.github.io,jzwlqx/denverdino.github.io,londoncalling/docker.github.io,rstacruz/compose,viranch/compose,londoncalling/docker.github.io,bdwill/docker.github.io,shubheksha/docker.github.io,menglingwei/denverdino.github.io,iamluc/compose,denverdino/denverdino.github.io,brunocascio/compose,mchasal/compose,benhamill/compose,au-phiware/compose,moxiegirl/compose,amitsaha/compose,albers/compose,runcom/compose,mnowster/compose,ZJaffee/compose,BSWANG/denverdino.github.io,KalleDK/compose,schmunk42/compose,jiekechoo/compose,KevinGreene/compose,DoubleMalt/compose,MSakamaki/compose,phiroict/docker,ionrock/compose,denverdino/compose,unodba/compose,TheDataShed/compose,vdemeester/compose,unodba/compose,sanscontext/docker.github.io,mnuessler/compose,gtrdotmcs/compose,bfirsh/fig,shin-/docker.github.io,docker-zh/docker.github.io,johnstep/docker.github.io,Yelp/docker-compose,mnuessler/compose,JimGalasyn/docker.github.io,menglingwei/denverdino.github.io,shin-/docker.github.io,BSWANG/denverdino.github.io,sdurrheimer/compose,phiroict/docker,alexisbellido/docker.github.io,Dakno/compose,jonaseck2/compose,kojiromike/compose,docker-zh/docker.github.io,josephpage/compose,rgbkrk/compose,aduermael/docker.github.io,charleswhchan/compose,troy0820/docker.github.io,sanscontext/docker.github.io,browning/compose,artemkaint/compose,anweiss/docker.github.io,nhumrich/compose,BSWANG/denverdino.github.io,mbailey/compose,mohitsoni/compose,tiry/compose,funkyfuture/docker-compose,mdaue/compose,troy0820/docker.github.io,anweiss/docker.github.io,mchasal/compose,shin-/docker.github.io,jzwlqx/denverdino.github.io,menglingwei/denverdino.github.io,twitherspoon/compose,alexandrev/compose,jzwlqx/denverdino.github.io,Chouser/compose,shin-/docker.github.io,LuisBosquez/docker.github.io,marcusmartins/compose,uvgroovy/compose,benhamill/compose,joeuo/docker.github.io,qzio/compose,aanand/fig,docker-zh/docker.github.io,danix800/docker.github.io,aduermael/docker.github.io,denverdino/docker.github.io,kikkomep/compose,thieman/compose,joeuo/docker.github.io,uvgroovy/compose,mbailey/compose,alunduil/fig,genki/compose,jeanpralo/compose,lmesz/compose,cclauss/compose,philwrenn/compose,joeuo/docker.github.io,bsmr-docker/compose,ph-One/compose,VinceBarresi/compose,marcusmartins/compose,alunduil/fig,ekristen/compose,LuisBosquez/docker.github.io,runcom/compose,vdemeester/compose,simonista/compose,JimGalasyn/docker.github.io,joaofnfernandes/docker.github.io,aanand/fig,docker/docker.github.io,michael-k/docker-compose,ekristen/compose,johnstep/docker.github.io,ggtools/compose,bobphill/compose,joaofnfernandes/docker.github.io,moxiegirl/compose,denverdino/denverdino.github.io,sanscontext/docker.github.io,prologic/compose,gdevillele/docker.github.io,mosquito/docker-compose,docker/docker.github.io,docker-zh/docker.github.io,dopry/compose,Katlean/fig,noironetworks/compose,iamluc/compose,cclauss/compose,jonaseck2/compose,d2bit/compose,kojiromike/compose,simonista/compose,ionrock/compose,tiry/compose,philwrenn/compose,bbirand/compose,Chouser/compose,saada/compose,RobertNorthard/compose,amitsaha/compose,tpounds/compose,jgrowl/compose,thaJeztah/docker.github.io,screwgoth/compose,bfirsh/fig,funkyfuture/docker-compose,glogiotatidis/compose,thaJeztah/docker.github.io,rillig/docker.github.io,anweiss/docker.github.io,j-fuentes/compose,londoncalling/docker.github.io,docker-zh/docker.github.io,KalleDK/compose,alexisbellido/docker.github.io,LuisBosquez/docker.github.io,BSWANG/denverdino.github.io,andrewgee/compose,viranch/compose,docker/docker.github.io,lukemarsden/compose,rgbkrk/compose,mnowster/compose,alexisbellido/docker.github.io,ralphtheninja/compose,noironetworks/compose,hoogenm/compose,phiroict/docker,menglingwei/denverdino.github.io,BSWANG/denverdino.github.io,mindaugasrukas/compose,mark-adams/compose,lukemarsden/compose,michael-k/docker-compose,bobphill/compose,jzwlqx/denverdino.github.io,GM-Alex/compose,DoubleMalt/compose,pspierce/compose,shin-/compose,swoopla/compose,ChrisChinchilla/compose,TomasTomecek/compose,phiroict/docker,goloveychuk/compose,JimGalasyn/docker.github.io,bsmr-docker/compose,aduermael/docker.github.io,dbdd4us/compose,londoncalling/docker.github.io,denverdino/docker.github.io