add release note for step header labels
concourse/concourse#4255
* Concourse now emits some useful metrics when [lidar](https://github.com/concourse/concourse/releases#v560-note-4202) is enabled: the size of the check queue, the number of checks queued per atc each tick, number of checks GCed at a time, checks started and checks finished. #4692
+#### <sub><sup><a name="4942" href="#4942">:link:</a></sup></sub> feature
+
+* The build page now shows text labels for different step types, like `get:`, `task:` and `set_pipeline:`, instead of the icons from previous versions. Hopefully this is more accessible and easier to interpret! #4942
+
#### <sub><sup><a name="stub-containerd" href="#stub-containerd">:link:</a></sup></sub> feature, stub
* The Concourse team is in the early stages of implementing a new backend for our container runtime based on [containerd](https://github.com/containerd/containerd), which is more featureful than the [guardian](https://github.com/cloudfoundry/guardian) we have relied on until now. We have not yet implemented all of the methods required by Garden, so the existing work (which can be enabled by passing the `--use-containerd` flag to `concourse worker`) is in a **non-functional state**. This work is tracked in [this project](https://github.com/concourse/concourse/projects/44). #4779, #4778, #4752, #4853, #4784
