Add docstring documenting the intended use of LabHubApp.

jupyterlab/labhubapp.py

@@ -1,5 +1,4 @@
 import os
-import warnings
 
 from traitlets import default
 
@@ -12,17 +11,25 @@
     raise ImportError('You must have jupyterhub installed for this to work.')
 else:
     class SingleUserLabApp(SingleUserNotebookApp, LabApp):
-
+        """
+        A sublcass of JupyterHub's SingleUserNotebookApp which includes LabApp
+        as a mixin. This makes the LabApp configurables available to the spawned
+        jupyter server.
+
+        If you don't need to change any of the configurables from their default
+        values, then this class is not necessary, and you can deploy JupyterLab
+        by ensuring that its server extension is enabled and setting the
+        `Spawner.default_url` to '/lab'.
+
+        If you do need to configure JupyterLab, then use this application by
+        setting `Spawner.cmd = ['jupyter-labhub']`.
+        """
         @default("default_url")
         def _default_url(self):
             """when using jupyter-labhub, jupyterlab is default ui"""
             return "/lab"
 
         def init_webapp(self, *args, **kwargs):
-            warnings.warn(
-                "SingleUserLabApp is deprecated, use SingleUserNotebookApp and set " + \
-                "c.Spawner.default_url = '/lab' in jupyterhub_config.py", DeprecationWarning
-            )
             super().init_webapp(*args, **kwargs)