ci(copybara): set up Zuul to sync with dotfiles-external

GitOrigin-RevId: 5d313e1f2dd57b3c9c8ee317a545559ab9a16c8f
diff --git a/.chezmoiignore b/.chezmoiignore
index 5081718..5a7f088 100644
--- a/.chezmoiignore
+++ b/.chezmoiignore
@@ -1,9 +1,12 @@
 LICENSE
 LICENSE.public
+playbooks
 README.md
 README.public.md
+roles
 .copybara
 .gitreview
+.zuul.yaml
 
 {{ if ne .chezmoi.os "darwin" }}
 .gitignore_global