Add Docker install instructions
Add Docker install instructions

bluecmd/prometheus-docs,dln/docs,fabxc/docs,prometheus/docs,tcolgate/docs,tcolgate/docs,dato/prometheus-docs,vic3lord/docs,open-falcon/open-falcon.github.io,ChaoticMind/docs,tcolgate/docs,vic3lord/docs,jimmidyson/docs,chosenken/docs,evanphx/docs,jmptrader/docs,ddfreyne/prometheus-docs,du2016/prometheus-docs,ddfreyne/prometheus-docs,vic3lord/docs,dln/docs,open-falcon/open-falcon.github.io,fabxc/docs,ChaoticMind/docs,prometheus/docs,pdbogen/docs,dln/docs,chosenken/docs,Cepave/openfalcon.io,fabxc/docs,du2016/prometheus-docs,evanphx/docs,jimmidyson/docs,jmptrader/docs,prometheus/docs,ChaoticMind/docs,pdbogen/docs,dato/prometheus-docs,jmptrader/docs,evanphx/docs,open-falcon/open-falcon.github.io,ddfreyne/prometheus-docs,bluecmd/prometheus-docs,bluecmd/prometheus-docs,Cepave/openfalcon.io,ddfreyne/prometheus-docs,dato/prometheus-docs,pdbogen/docs,jimmidyson/docs,chosenken/docs,Cepave/openfalcon.io,chosenken/docs,du2016/prometheus-docs