Add note about manager in the Lab UI in docs

Author: mahendrapaipuri

docs/source/_static/images/labextension-manager.gif

@@ -27,3 +27,26 @@ buttons in JupyterLab's Launcher panel for registered server processes.
 ```
 
 Clicking on them opens the proxied application in a new browser window.
+
+Currently running proxy applications are shown in the running sessions tab
+under "Server Proxy Apps" section.
+
+```{image} _static/images/labextension-manager.gif
+
+```
+
+As shown in the GIF, users can consult the metadata of each running proxy
+application by hovering over the name of the proxy. It is also possible to
+terminate the proxy application using Shut Down button.
+
+```{note}
+When the user clicks Shut Down button to terminate a proxy application,
+a `SIGTERM` signal is sent to the application. It is the user's responsibility
+to ensure that the application exits cleanly with a `SIGTERM` signal. There
+are certain applications (like MLflow) that cannot be terminted with `SIGTERM`
+signal and in those cases, the users can setup wrapper scripts to trap the
+signal and ensure clean teardown of the application.
+```
+
+Only proxy applications that are started by `jupyter-server-proxy` are shown
+in the running Server Proxy Apps section.