util/docker/coreboot-jenkins-node: add linkchecker

The linkchecker tool is now being used to find broken links in our
websites.  Since it's not needed for building anything, just add it to
the jenkins-node Dockerfile instead.

Signed-off-by: Martin Roth <martin@coreboot.org>
Change-Id: Iac2246b5378e556b5cd9f2107fc5a7e51d583b5b
Reviewed-on: https://review.coreboot.org/c/coreboot/+/62445
Reviewed-by: Felix Singer <felixsinger@posteo.net>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

util/docker/coreboot-jenkins-node/Dockerfile

@@ -28,6 +28,7 @@ RUN apt-get -y update && \
 	parallel \
 	meson ninja-build \
 	sdcc \
+	linkchecker \
 	lua5.3 liblua5.3-dev default-jre-headless openssh-server && \
 	apt-get clean