Update changelog and readme to reflect migration

CHANGELOG.md

@@ -6,8 +6,19 @@
 
 ## Breaking Changes
 
+- Migration from Pusher to independent org may have introduced breaking changes for your environment.
+  - See the changes listed below for PR [#464](https://github.com/oauth2-proxy/oauth2-proxy/pull/464) for full details
+  - Binaries renamed from `oauth2_proxy` to `oauth2-proxy`
+
 ## Changes since v5.1.0
 
+- [#464](https://github.com/oauth2-proxy/oauth2-proxy/pull/464) Migrate to oauth2-proxy/oauth2-proxy (@JoelSpeed)
+  - Project renamed from `pusher/oauth2_proxy` to `oauth2-proxy`
+  - Move Go import path from `github.com/pusher/oauth2_proxy` to `github.com/oauth2-proxy/oauth2-proxy`
+  - Remove Pusher Cloud Team from CODEOWNERS
+  - Release images moved to `quay.io/oauth2-proxy/oauth2-proxy`
+  - Binaries renamed from `oauth2_proxy` to `oauth2-proxy`
+
 # v5.1.0
 
 ## Release Hightlights

README.md

@@ -12,6 +12,9 @@ to validate accounts by email, domain or group.
 Versions v3.0.0 and up are from this fork and will have diverged from any changes in the original fork.
 A list of changes can be seen in the [CHANGELOG](CHANGELOG.md).
 
+**Note:** This project was formerly hosted as `pusher/oauth2_proxy` but has been renamed as of 29/03/2020 to `oauth2-proxy/oauth2-proxy`.
+Going forward, all images shall be available at `quay.io/oauth2-proxy/oauth2-proxy` and binaries wiil been named `oauth2-proxy`.
+
 ![Sign In Page](https://cloud.githubusercontent.com/assets/45028/4970624/7feb7dd8-6886-11e4-93e0-c9904af44ea8.png)
 
 ## Installation