Document show_host_usage configuration option in README (#218)

* updates readme with show_host_usage feature

* Lint

* Move the addition to the configuration section

---------

Co-authored-by: Michał Krassowski <5832902+krassowski@users.noreply.github.com>

README.md

@@ -103,6 +103,14 @@ The threshold for this warning can be configured as a fraction of the memory lim
 If you want to flash the warning to the user when they are within 10% of the memory limit, you
 can set the parameter `--ResourceUseDisplay.mem_warning_threshold=0.1`.
 
+### Host information
+
+If you want to hide host information from the Kernel Usage sidebar
+you can set `--ResourceUseDisplay.show_host_usage=False` to hide `Host CPU` and `Host Virtual Memory` information.
+The default is set as `True`, i.e. show all the information.
+
+![Screenshot for kernel usage with limited info](./doc/kernel-usage-limited-info.png)
+
 ### CPU Usage
 
 `jupyter-resource-usage` can also track CPU usage and report a `cpu_percent` value as part of the `/api/metrics/v1` response.