Add release notes for edge-18.12.4 release
+## edge-18.12.4
+
+Upgrade notes: The control plane components have been renamed as of the
+edge-18.12.1 release to reduce possible naming collisions. To upgrade an
+older installation, see the [Upgrade Guide](https://linkerd.io/2/upgrade/).
+
+* CLI
+ * Add `--routes` flag to the `linkerd top` command, for grouping table rows
+ by route instead of by path
+ * Update Prometheus configuration to automatically load `*_rules.yml` files
+ * Remove TLS column from the `linkerd routes` command output
+* Web UI
+ * Restore unmeshed resources in the network graph on the resource detail page
+ * Reduce the overall size of the asset bundle for the web frontend
+* Proxy
+ * Improve configuration of the PeakEwma load balancer
+
+Special thanks to @radu-matei for cleaning up a whole slew of Go lint warnings,
+and to @jonrichards for improving the Rust build setup!
+
## edge-18.12.3
Upgrade notes: The control plane components have been renamed as of the
