Add link to last passing commit in README

The CI status badge is almost always grey, which isn't super useful. There's got to be a better way to do this, but this seems useful in the meantime

Closes #163

COPYBARA_INTEGRATE_REVIEW=https://github.com/google/iree/pull/163 from google:last-passing-link 4c6de6ac43d4aa1e608dde3670b9abddd0ad2b3b
PiperOrigin-RevId: 282831086
diff --git a/README.md b/README.md
index 20bf239..41a7c81 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,9 @@
 
 ![ci-status](https://github.com/google/iree/workflows/Continuous%20Integration/badge.svg)
 
+To find the last passing commit, choose the latest passing run
+[here](https://github.com/google/iree/actions?query=branch%3Amaster+event%3Apush+is%3Asuccess).
+
 ## Table of Contents
 
 -   [Quickstart](#quickstart)