Make libforwarder buildable

Bug: 340126051
Test: m libforwarder
Change-Id: Ie427efeb5f326ec4bd1dfb84ac7ee8c03b9e0248
diff --git a/libs/libforwarder/src/lib.rs b/libs/libforwarder/src/lib.rs
index 9c2c7a3..bcce689 100644
--- a/libs/libforwarder/src/lib.rs
+++ b/libs/libforwarder/src/lib.rs
@@ -15,5 +15,7 @@
 // Copied from ChromiumOS with relicensing:
 // src/platform2/vm_tools/chunnel/src/lib.rs
 
+//! Library for stream socket forwarding.
+
 pub mod forwarder;
 pub mod stream;