Allow copybara to self-approve docs

We can't put this directly in docs/OWNERS because it will get deleted on sync.

Change-Id: I3f8c6787da1a560d3324fd97005933b69d67b644
Test: copybara
diff --git a/OWNERS b/OWNERS
index b6e6906..12e1923 100644
--- a/OWNERS
+++ b/OWNERS
@@ -28,3 +28,6 @@
 per-file *settings.gradle = set noparent
 per-file *settings.gradle = [email protected], [email protected], [email protected]
 per-file *libraryversions.toml = [email protected]
+
+# Copybara can self-approve CLs within synced docs.
+per-file docs/... = [email protected]
\ No newline at end of file