document how to run weave when docker access is root-only
document how to run weave when docker access is root-only

Closes #1186.

achanda/weave,achanda/weave,weaveworks/weave,aaam/weave,weaveworks/weave,squaremo/weave,beni55/weave,kidaa/weave,paladin74/weave,kidaa/weave,philipz/weave,BWITS/weave,awh/weave,kidaa/weave,n054/weave,rade/weave,aaam/weave,squaremo/weave,bboreham/weave,beni55/weave,paladin74/weave,rade/weave,bboreham/weave,paulbellamy/weave,BWITS/weave,dpw/weave,rade/weave,awh/weave,weaveworks/weave,narry/weave,awh/weave,bboreham/weave,BWITS/weave,n054/weave,philipz/weave,tomwilkie/weave,tomwilkie/weave,beni55/weave,bboreham/weave,aaam/weave,kidaa/weave,awanke/weave,achanda/weave,squaremo/weave,awanke/weave,cgvarela/weave,achanda/weave,cgvarela/weave,tomwilkie/weave,narry/weave,cgvarela/weave,aaam/weave,dpw/weave,narry/weave,weaveworks/weave,cgvarela/weave,tomwilkie/weave,paulbellamy/weave,awh/weave,philipz/weave,awanke/weave,tomwilkie/weave,squaremo/weave,aaam/weave,achanda/weave,awanke/weave,dpw/weave,cgvarela/weave,dpw/weave,squaremo/weave,bboreham/weave,BWITS/weave,paulbellamy/weave,dpw/weave,rade/weave,paulbellamy/weave,BWITS/weave,rade/weave,paladin74/weave,narry/weave,philipz/weave,narry/weave,n054/weave,n054/weave,n054/weave,beni55/weave,philipz/weave,kidaa/weave,awanke/weave,awh/weave,paladin74/weave,beni55/weave,paladin74/weave