meta: add codereview.cfg

Change-Id: I03a5fb396e8fa83b6690600f3198419d30431c8e
Reviewed-on: https://upspin-review.googlesource.com/14922
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/codereview.cfg b/codereview.cfg
new file mode 100644
index 0000000..e67a9bc
--- /dev/null
+++ b/codereview.cfg
@@ -0,0 +1 @@
+issuerepo: upspin/upspin