Add some docs

Author: yuvipanda

README.md

@@ -1,2 +1,21 @@
 # jupyterhub-simulator
-Newer performance simulator for testing workloads on a JupyterHub
+
+Newer performance simulator for testing workloads on a JupyterHub.
+
+Successor to [hubtraf](https://github.com/yuvipanda/hubtraf).
+
+## Design goals
+
+- Test spawning a large number of users in a short period of time with some tuning knobs,
+  to see how the infrastructure as a whole responds.
+- Support all possible authentication types by simply using the JupyterHub API directly. We
+  spawn multiple servers by using named server support in JupyterHub, something that was not
+  yet implemented in the initial design time of hubtraf.
+- Any user can run these tests, limited only by their hub's max number of per-user named servers.
+
+## TODO
+
+- Support spawning on hubs with profile lists.
+- Support passing on to [playwright-python](https://playwright.dev/python/docs/intro) after the
+  server has been started, so we can more accurately test user workflows directly.
+- Output telemetry data in a fashion that can be easily graphed.