Update docker-build/README.md

Co-authored-by: Will Kahn-Greene <willkg@users.noreply.github.com>

Author: grahamalama

docker-build/README.md

@@ -1,6 +1,6 @@
 # docker-build
 
-This GitHub Action is designed to build a Docker container image, providing standard Mozcloud tags for supported registries. It outputs a list of images to be consumed by the [docker-push](../docker-push/README.md) action
+This GitHub Action is designed to build a Docker container image, providing standard MozCloud tags for supported registries. It outputs a list of images in `image_tags` to be consumed by the [docker-push](../docker-push/README.md) action
 
 ## Inputs