doc/improve-docker-doc: add notice for nginx error message when port 80 is already used

3 jobs for doc/improve-docker-doc in 2 minutes and 37 seconds (queued for 1 second)
Status Job ID Name Coverage
  Test Tools
passed #696950
test_tools

00:00:10

 
  Tgz Release
passed #696951
cidocker
build_doc

00:02:27

 
  Deploy Prod
manual #696952
allowed to fail manual
deploy_doc