docker: add license info

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/docker/docker.mk

@@ -8,6 +8,10 @@ DOCKER_VERSION = 1.5
 DOCKER_SITE = http://icculus.org/openbox/2/docker
 DOCKER_DEPENDENCIES = host-pkgconf libglib2 xlib_libX11
 
+DOCKER_LICENSE = GPLv2+
+# The 'or later' is specified at the end of the README, so include that one too.
+DOCKER_LICENSE_FILES = COPYING README
+
 define DOCKER_BUILD_CMDS
 	$(TARGET_CONFIGURE_OPTS) $(TARGET_MAKE_ENV) $(MAKE) -C $(@D) \
 		XLIBPATH=$(STAGING_DIR)/usr/lib