doc/improve-docker-doc: fix command line code display error

3 jobs for doc/improve-docker-doc in 1 minute and 56 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test Tools
passed #696947
test_tools

00:00:08

 
  Tgz Release
passed #696948
cidocker
build_doc

00:01:47

 
  Deploy Prod
manual #696949
allowed to fail manual
deploy_doc