website: update info on nersc and jupyterhub

Author: huiwanpnnl

docs/nersc/JupyterHub_control_panel_with_stop_button.png

@@ -27,20 +27,50 @@ or how to have their own installation are referred to [this page](installation_a
   and shows a URL starting with `https://`.
   A click on the URL will bring up the graphical UI in a brower window.
 
-::: tip Tip: Choosing a server for your analysis session
+::: tip Tip 1: Choosing a server for your analysis session.
 JupyterHub's control panel allows users to choose from serveral different types of resources
 for their computing and analyais needs, including, e.g., login node, shared GPU node,
-exclusive nodes, etc. Since login nodes are shared by users and hence can get very busy
-or run into memory constraints, we recommend that users choose a shared GPU node
-or an exclusive node and user our tools there.
+exclusive nodes, as explained in [NERSC's documentation](https://docs.nersc.gov/services/jupyter/reference/).
 
+Since login nodes are shared by users and hence can get very busy or run into memory constraints,
+and since our tools can make use of GPUs for interactive rendering.
+we recommend that users choose a shared GPU node or an exclusive GPU node.
+
+Keep in mind, though, that time spent on shared GPU nodes or exclusive nodes
+will be charged to your project's allocation.
+:::
+
+::: tip Tip 2: Same executable for all kinds of nodes.
 Regardless of which type of node is chosen, the same commands (as listed above)
 are used to launch our tools in the QuickView family.
 :::
 
+::: tip Tip 3: No need to manually load `conda`.
+When one of the commands provided above is used to lunch tools in the QuickView family,
+there is no need to manually load `conda` or the conda environment that our tools are installed in.
+This is because the above-mentioned commands are in fact scripts that have included those steps.
+:::
+
+::: warning Reminder: Shut down the server when you are done.
+After finishing your analysis, please remember to shut down the connection to your selected
+server (node) to stop the charging of ours to your project's allocation. 
+This is explained at the end of
+[this video](https://docs.nersc.gov/beginner-guide/#keypad-entry-log-in-using-jupyter),
+and here is a recap of the steps (clicks):
+- go to the JupytherHub window/tab in your browser,
+- click `File`,
+- scroll down and choose `Hub Control Panel`,
+- in the Control Panel that brought up in a new brower tab/window, click on the red "stop" button
+  for the server to shut down. An example is shown in the screenshot below.
+
+![JupyterHub_control_panel_with_stop_button.png](/nersc/JupyterHub_control_panel_with_stop_button.png)
+:::
+
 ## For NERSC user's who have not used JupyterHub
 
-Please visit [NERSC's Jupyter documentation](https://docs.nersc.gov/services/jupyter/)
+Please see this section of
+[NERSC's documentation](https://docs.nersc.gov/beginner-guide/#keypad-entry-log-in-using-jupyter),
+especially the video "How to log in to Perlmutter with Jupyter",
 to learn how to use the service.
 
 ## If you do not yet have any user account at  NERSC