Sidebar Custom HTML properties
| type | (string) required, the item type, set it to "customHTML". If not specified - the "navItem" type is applied by default. |
| id | (string, number) the id of an item, auto-generated if not set |
| parent | (string) the parent of the item |
| html | (string) a string with HTML that should be inserted into the item |
| css | (string|string[]) adds style classes |
| hidden | (boolean) defines whether an item is hidden |