Update Dockerfile (correct typo)

4 jobs for master in 6 minutes and 46 seconds (queued for 15 seconds)
Status Job ID Name Coverage
  Build Docker Image
passed #7615
manual
build_docker_image_

00:04:30

 
  Generate Config Files
manual #7616
allowed to fail manual
generate-config-files
 
  Deploy
passed #7617
manual
deploy

00:02:15

manual #7618
allowed to fail manual
rsync-files-on-server