ORFS: document how to test with locally built docker image

Signed-off-by: Øyvind Harboe <[email protected]>

MODULE.bazel

@@ -19,6 +19,15 @@ git_override(
     remote = "https://github.com/The-OpenROAD-Project/bazel-orfs.git",
 )
 
+# TL;DR to test with a locally built ORFS docker image, update below after building
+# locally and run `bazel mod tidy`:
+#
+# $ ./build_openroad.sh
+# [lots of output deleted]
+# 23 naming to docker.io/openroad/flow-ubuntu22.04-builder:7582cf done
+# $ docker buildx imagetools inspect openroad/flow-ubuntu22.04-builder --format "{{json .Manifest.Digest}}"
+# "sha256:5d4d20d3d5638fa5c79b05c6f9b240c7e5691bf8b6c47c9a46d9bb0e0d53bb09"
+# $ bazel mod tidy
 orfs = use_extension("@bazel-orfs//:extension.bzl", "orfs_repositories")
 orfs.default(
     image = "openroad/orfs:v3.0-1114-g46acc762",