removing the exclaimation mark from our hello-world examples, some users get trapped by the shell

Docker-DCO-1.1-Signed-off-by: SvenDowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Lowercase world, because its not important.

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@docker.com> (github: SvenDowideit)
Merge pull request #6788 from SvenDowideit/remote-bang-from-hello-world

removing the exclaimation mark from our hello-world examples, some users...