Update builder.md (cherry picked from commit 831066337743fc29ff122fce51afe44b8b3b3ba9) Signed-off-by: Sebastiaan van Stijn <github@gone.nl> (cherry picked from commit bc66821abbcf50c721ce9b8f52b339fda102d389) Signed-off-by: Tibor Vass <tibor@docker.com>