update auth docu

doc/authentication.rst

@@ -1,8 +1,8 @@
 Enabling Authentication
 =======================
 
-By default BinderHub runs without authentication.
-For each launch, BinderHub creates a temporary user and starts a server for that user.
+By default BinderHub runs without authentication and
+for each launch it creates a temporary user and starts a server for that user.
 
 In order to enable authentication, you need to add the following into BinderHub configuration:
 
@@ -21,6 +21,7 @@ In order to enable authentication, you need to add the following into BinderHub
           binder:
             #url: "http://<external ip of binder service>"
             oauth_client_id: "binder-oauth-client-test"
+            oauth_redirect_uri: ??
 
       auth: {}
 
@@ -40,7 +41,7 @@ BinderHub starts notebook servers with `jupyter-notebook` command by default.
 When authentication is not enable, this is good because users don't need to have interaction with hub and
 notebook servers need to be independent of hub.
 When authentication is enabled with the configuration above, users can still launch binder sessions
-under `/services/binder/`, but because notebook server is independent from hub there will be some problems:
+under `/services/binder/` but because notebook server is independent from hub there will be some problems:
 
 - Logout button in Notebook UI won't logout user from hub
 - User won't be able to manage notebook server with hub home actions
@@ -70,11 +71,11 @@ Add the following configuration to make notebook servers aware of hub:
     `jupyterhub-singleuser` requires `JupyterHub` installed in user server images,
     which is not installed by `repo2docker` by default.
 
-Authentication with named servers:
-----------------------------------
+Authentication with named servers
+---------------------------------
 
 With above configuration Binderhub limits each authenticated user to start one server at a time.
-When user already has a running server, BinderHub returns an error.
+When user already has a running server, BinderHub displays an error message.
 
 If you want to have users be able to launch multiple servers, you have to enable named servers
 on JupyterHub:
@@ -85,15 +86,8 @@ on JupyterHub:
       hub:
         allowNamedServers: true
 
-.. https://kubernetes.io/docs/concepts/overview/working-with-objects/names/
-.. https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/
-.. TODO try again and see the exact error
-
-.. warning::
-    Kubernetes has 63?253 char limit for pod and pvc names.
-
-    c.KubeSpawner.pod_name_template = 'jupyter-{userid}{servername}
-
-    pvcNameTemplate: claim-{userid}{servername}
+.. note::
+    BinderHub assigns a unique name to each server with max 40 characters.
 
-    volumeNameTemplate: volume-{userid}{servername}
+.. https://kubernetes.io/docs/concepts/overview/working-with-objects/names/
+.. https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/