Add a comment to kBBRv2 which explains that it's essentially BBRv3
and a TODO to rename it when the implementation is complete.

PiperOrigin-RevId: 605616858

quiche/quic/core/quic_types.h

diff --git a/quiche/quic/core/quic_types.h b/quiche/quic/core/quic_types.h
index 119b266..96e075c 100644
--- a/quiche/quic/core/quic_types.h
+++ b/quiche/quic/core/quic_types.h
@@ -451,7 +451,8 @@
   kBBR,
   kPCC,
   kGoogCC,
-  kBBRv2,
+  kBBRv2,  // TODO(rch): This is effectively BBRv3. We should finish the
+           // implementation and rename this enum.
 };
 
 QUICHE_EXPORT std::string CongestionControlTypeToString(