Document delegate command line usage

[Danack]

Because jumping through imagemagick hoops is dumb.

inkscape "m.svg" --export-filename="/var/app/bugReports/gh551/output_inkscape_directly.png" \
  --export-dpi="96" \
  --export-background="white" \
  --export-background-opacity="255" > inkscape_output.txt 2>&1