Nested Menu for Home Container web item

[Deleted user]

I am trying to create a Home Container Menu following this URL

https://developer.atlassian.com/cloud/jira/platform/home-container/

I am interested in creating a nested menu, very similar to "Jira Settings" which will show admin related menu items under it. 

Documentation says: 

The home container location only supports web items, however you can create additional web items that reference the first web item’s key as their location in order to support nested navigation.

• Key of the initial web item with the system.top.navigation.bar

What does this above line mean? how should "key" be combined with "system.top.navigation.bar" ?

Can someone help me with an example? I have tried "system.top.navigation.bar/{key}" but that did not help.