Docker params

[chiarcos]

Dear Johannes, thanks for your nice work!
A minor suggestion: You might want to omit -d from the docker call (or describe what it does), because otherwise people won't get out error logs ;)

Otherwise, your error logs are helpful, thanks for that. I just got a head id must be different from word id in line (52).

[jheinecke]

Hi Christian,
thanks for the feedback. I added a simple explanation on the-d option.