Release: Remove non-existing target from Makefile

Remove the unnecessary comment while being there.

Change-Id: I25411e94aabcbc0118e73cc376e94aa359a41ea6
diff --git a/jenkins-docker/slave-release/Makefile b/jenkins-docker/slave-release/Makefile
index d958f24..81f2c81 100644
--- a/jenkins-docker/slave-release/Makefile
+++ b/jenkins-docker/slave-release/Makefile
@@ -1,8 +1,6 @@
 NO_CACHE=false
 IMAGE=gerritforge/gerrit-release-bazel:debian-buster
 
-# Targets
-
 build:
 	docker build --no-cache=$(NO_CACHE) -t ${IMAGE} .
 
@@ -12,5 +10,4 @@
 clean:
 	docker rmi -f ${IMAGE}
 
-.PHONY: clean image publish
-
+.PHONY: clean publish