Remove redundant command

[Stolz]

mkdir -p will create all missing parent directories, so this line is redundant since next line includes the same folder as parent

[TimWolla]

Thanks for catching this. I'd rather just remove the -p for the second call though. I would like the creation of the webroot (/var/www/html/) to be explicit.

Also the change would need to be applied to the fastcgi Dockerfile as well.

Would you like to handle the changes? Otherwise I'll just commit this myself.