Update request-response changelog.
# 0.3.0 [unreleased]
+- Add support for opt-in request-based flow-control to any
+ reqyest-response protocol via `RequestResponse::throttled()`.
+ [PR 1726](https://github.com/libp2p/rust-libp2p/pull/1726).
+
- Update `libp2p-swarm` and `libp2p-core`.
# 0.2.0 [2020-08-18]
