Update CHANGES for v0.5.0 (#1273)

CHANGES.md

@@ -1,3 +1,34 @@
+## v0.5.0
+
+Conduit v0.5.0 introduces a new, experimental feature that automatically
+enables Transport Layer Security between Conduit proxies to secure
+application traffic. It also adds support for HTTP protocol upgrades, so
+applications that use WebSockets can now benefit from Conduit.
+
+* Security
+  * **New** `conduit install --tls=optional` enables automatic, opportunistic
+    TLS. See [the docs][auto-tls] for more info.
+* Production Readiness
+  * The proxy now transparently supports HTTP protocol upgrades to support, for
+    instance, WebSockets.
+  * The proxy now seamlessly forwards HTTP `CONNECT` streams.
+  * Controller services are now configured with liveness and readiness probes.
+* User Interface
+  * `conduit stat` now supports a virtual `authority` resource that aggregates
+    traffic by the `:authority` (or `Host`) header of an HTTP request.
+  * `dashboard`, `stat`, and `tap` have been updated to describe TLS state for
+    traffic.
+  * `conduit tap` now has more detailed information, including the direction of
+    each message (outbound or inbound).
+  * `conduit stat` now more-accurately records histograms for low-latency services.
+  * `conduit dashboard` now includes error messages when a Conduit-enabled pod fails.
+* Internals
+  * Prometheus has been upgraded to v2.3.1.
+  * A potential live-lock has been fixed in HTTP/2 servers.
+  * `conduit tap` could crash due to a null-pointer access. This has been fixed.
+
+[auto-tls]: docs/automatic-tls.md
+
 ## v0.4.4
 
 Conduit v0.4.4 continues to improve production suitability and sets up internals for the