generate-env: Use <<-EOF to indent the heredoc

Indentation is helpful to know a function's scope. Not indenting the
heredoc makes scanning harder.

Signed-off-by: Manuel Mendez <mmendez@equinix.com>

generate-env.sh

@@ -53,7 +53,8 @@ generate_env() (
 	tink_password=$(generate_password)
 	local registry_password
 	registry_password=$(generate_password)
-	cat <<EOF
+
+	cat <<-EOF
 		# Tinkerbell Stack version
 
 		export OSIE_DOWNLOAD_LINK=${OSIE_DOWNLOAD_LINK}