nope, echo -e isn't portable

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@home.org.au> (github: SvenDowideit)
Merge pull request #4437 from SvenDowideit/tweak-DCO-hook-for-windows

Replace `echo -e` with the portable `{ echo; echo ...; }`