add notes on custom bob screen

Author: gilesknap

docs/images/custom_bob.png

@@ -56,6 +56,19 @@ ec up -d
 
 Phoebus will be launched and attempt to load the bob file called **opi/ioc/index.bob**. The **opi** folder is a place where the author of this generic IOC could place some screens. The subfolder **ioc** is not committed to git and is where the IOC instance will place its autogenerated engineering screens. The autogenerated screens always include and index.bob which is the entry point to all other autogenerated screens.
 
+## /workspaces in Phoebus Container
+
+Just like the developer container itself, the Phoebus container mounts the folder above **ioc-adsimdetector** into the container as **/workspaces**. This means you can access bob files from peer projects.
+
+The autogenerated engineering screens currently show the image array as a list of integers. But we already had a nice screen for displaying an overview of the PVs, including an image widget for the image array. That screen was made for the same IOC instance we are currently running inside of the developer container.
+
+To access the screen, chose `File -> Open` in phoebus and navigate to **/workspaces/t01-services/opi/demo-simdet.bob** file. This will open the screen in phoebus and allow you to view the sample image.
+
+:::figure
+![Phoebus Screen](../images/custom_bob.png)
+Example overview screen for bl01t-ea-cam-01
+:::
+
 ## Using Host Machine Tools
 
 If you have EPICS tools installed on the host machine then those can now also be used.