Add back infra/config

It still contains tricium configs, so we may need to edit it.

Change-Id: Id6673ccba91102374573d9152130b6468d6c899c
diff --git a/infra b/infra
index 8339ad0..8421d7b 100644
--- a/infra
+++ b/infra
@@ -16,6 +16,10 @@
              path="fuchsia/infra"
              remote="https://fuchsia.googlesource.com/infra/infra"
              gerrithost="https://fuchsia-review.googlesource.com"/>
+    <project name="fuchsia/config"
+             path="fuchsia/config"
+             remote="https://fuchsia.googlesource.com/infra/config"
+             gerrithost="https://fuchsia-review.googlesource.com"/>
     <project name="fuchsia/prebuilt"
              path="fuchsia/prebuilt"
              remote="https://fuchsia.googlesource.com/infra/prebuilt"