Merge branch 'kh/submittingpatches-trailers'

The trailer sections in SubmittingPatches have been updated to encourage use of standard trailers. * kh/submittingpatches-trailers: SubmittingPatches: note that trailer order matters SubmittingPatches: be consistent with trailer markup SubmittingPatches: document Based-on-patch-by trailer SubmittingPatches: discourage common Linux trailers SubmittingPatches: encourage trailer use for substantial help