Clarify hasSubItems usage in App Side Nav (#3134)

Co-authored-by: Kristin Bradley <kristin.bradley@hashicorp.com>

Author: jorytindall

website/docs/components/app-side-nav/partials/code/how-to-use.md

@@ -221,14 +221,12 @@ If you find yourself in the situation of wanting/needing to customize or change
 
 ### Accessibility
 
+Since this component is layout-only, there are no built-in accessibility features: you are responsible for making sure your custom App Side Nav implementation is conformant to the WCAG requirements.
+
 #### `aria` attributes
 
 The App Side Nav component already provides some of the required `aria` attributes. But other attributes are needed when declaring its content. Please refer to the [Accessibility](/components/app-side-nav?tab=accessibility) section for more details.
 
 #### Animations
 
 Animations and transition on the component will not take place if the user has `prefers-reduced-motion` enabled in their browser or operating system.
-
-### Accessibility
-
-Since this component is layout-only, there are no built-in accessibility features: you are responsible for making sure your custom App Side Nav implementation is conformant to the WCAG requirements.

website/docs/components/app-side-nav/partials/guidelines/guidelines.md

@@ -26,7 +26,6 @@ The body consists of a group of sections with vertical lists of links, typically
 
 ![App Side Nav section without a title](/assets/components/app-side-nav/section-without-title.png)
 
-
 ### List items
 
 #### Without icon
@@ -69,7 +68,14 @@ Don’t override the color of the icon within the list item or incorporate a bra
 
 Use `hasSubItems` to show or signify that a link has a nested level of navigation.
 
-!["Settings" list item with a right arrow icon to show that it has sub-items](/assets/components/app-side-nav/list-item-with-nested-items.png)
+!["Settings" list item with a right arrow icon to show that it has sub-items, with an example of the list of sub-items within settings; Organization Settings including "General", "Teams", and "Runs".](/assets/components/app-side-nav/list-item-with-nested-items.png)
+
+!!! Dont
+
+Don’t use `hasSubItems` to indicate that a link in the App Side Nav directs to a page _containing_ a list of links within the main content area of the page itself.
+
+![An example of a list item with the hasSubItems property with links directly within the page linking to other parts of the application](/assets/components/app-side-nav/list-item-nested-items-dont.png)
+!!!
 
 #### External links