Add note about failing CI (#1790)

fhinkel · Ace Nassri · web-flow · commit 5e2bbb2784bb · 2020-05-08T11:22:40.000-04:00
Co-authored-by: Ace Nassri &lt;anassri@google.com&gt;
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
@@ -42,3 +42,6 @@ directory.
         npm run lint
 
 [cloud]: https://cloud.google.com/
+
+## Failing CI
+`Required` tests need to pass. Tests that are not required are expected to fail, they are usually work in progress. 
