build-unit-test-docker: fix default docker in comments

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ie5f34b4886105e378d049d4e056c3cdb138b81a4
diff --git a/scripts/build-unit-test-docker b/scripts/build-unit-test-docker
index 24c42d9..bcc337d 100755
--- a/scripts/build-unit-test-docker
+++ b/scripts/build-unit-test-docker
@@ -6,7 +6,7 @@
 #   DOCKER_IMG_NAME:  <optional, the name of the docker image to generate>
 #                     default is openbmc/ubuntu-unit-test
 #   DISTRO:           <optional, the distro to build a docker image against>
-#                     default is ubuntu:focal
+#                     default is ubuntu:groovy
 #   FORCE_DOCKER_BUILD: <optional, a non-zero value with force all Docker
 #                     images to be rebuilt rather than reusing caches.>
 #   BUILD_URL:        <optional, used to detect running under CI context