command/format: Show resource diff with header "comment"
command/format: Show resource diff with header "comment"

This extra comment line gives us a place to show the full resource address
(since the block header line only includes type and name) and also allows
us to explain in long form the meaning of the change icon on the following
line.

hashicorp/terraform,tpounds/terraform,VladRassokhin/terraform,apparentlymart/terraform,VladRassokhin/terraform,iljaskevic/terraform,gechr/terraform,heimweh/terraform,brandontosch/terraform,rnaveiras/terraform,iljaskevic/terraform,rnaveiras/terraform,brandontosch/terraform,apparentlymart/terraform,ewbankkit/terraform,pradeepbhadani/terraform,drebes/terraform,ewbankkit/terraform,drebes/terraform,pryorda/terraform,pryorda/terraform,luis-silva/terraform,heimweh/terraform,nlamirault/terraform,pdecat/terraform,heimweh/terraform,gechr/terraform,hashicorp/terraform,pradeepbhadani/terraform,brandontosch/terraform,youhong316/terraform,mattray/terraform,pryorda/terraform,tpounds/terraform,drebes/terraform,ewbankkit/terraform,apparentlymart/terraform,hashicorp/terraform,luis-silva/terraform,heimweh/terraform,tommynsong/terraform,apparentlymart/terraform,pdecat/terraform,iljaskevic/terraform,drebes/terraform,tommynsong/terraform,pradeepbhadani/terraform,tpounds/terraform,nlamirault/terraform,youhong316/terraform,VladRassokhin/terraform,luis-silva/terraform,mattray/terraform,tpounds/terraform,youhong316/terraform,nlamirault/terraform,tommynsong/terraform,mattray/terraform,ewbankkit/terraform,youhong316/terraform,heimweh/terraform,rnaveiras/terraform,gechr/terraform,brandontosch/terraform,luis-silva/terraform,brandontosch/terraform,VladRassokhin/terraform,apparentlymart/terraform,mattray/terraform,pdecat/terraform,iljaskevic/terraform,pdecat/terraform