Add .include-dark to hybrid-nav image references

Enables dark mode variants for nav-bar-hybrid, nav-bar-hybrid-sidebar,
and nav-bar-hybrid-dropdown screenshots.

Author: cderv

docs/websites/website-navigation.qmd

@@ -282,11 +282,11 @@ If you have a website with dozens or even hundreds of pages, you will likely wan
 
 To do this, provide a group of `sidebar` entries and link each group of `sidebar` entries with a `navbar` entry by matching their `title`s and listing the page linked from the `navbar` as the first content in the `sidebar` group. For example, if you are using the [Diátaxis Framework](https://diataxis.fr/) for documentation, you might have separate sections for tutorials, how-to guides, explanations, and reference documents, your page might look like the following.
 
-![](images/nav-bar-hybrid.png){fig-alt="A navigation bar titled 'ProjectX' on the left. To the right of the title are the menu items 'Home', 'Tutorials', 'How-To', 'Fundamentals', and 'Reference'. There is a search bar on the far right side of the navigation bar."}
+![](images/nav-bar-hybrid.png){.include-dark fig-alt="A navigation bar titled 'ProjectX' on the left. To the right of the title are the menu items 'Home', 'Tutorials', 'How-To', 'Fundamentals', and 'Reference'. There is a search bar on the far right side of the navigation bar."}
 
 With hybrid navigation, if then you click on, say, Tutorials, you might land in a page like the following.
 
-![](images/nav-bar-hybrid-sidebar.png){fig-alt="A navigation bar titled 'ProjectX' on the left. To the right of the title are the menu items 'Home', 'Tutorials', 'How-To', 'Fundamentals', and 'Reference'. There is a search bar on the far right side of the navigation bar. The contents of the 'Tutorials' page is shown, with the sidebar showing the items 'Tutorials', 'Tutorial 1', and 'Tutorial 2'."}
+![](images/nav-bar-hybrid-sidebar.png){.include-dark fig-alt="A navigation bar titled 'ProjectX' on the left. To the right of the title are the menu items 'Home', 'Tutorials', 'How-To', 'Fundamentals', and 'Reference'. There is a search bar on the far right side of the navigation bar. The contents of the 'Tutorials' page is shown, with the sidebar showing the items 'Tutorials', 'Tutorial 1', and 'Tutorial 2'."}
 
 To achieve this layout, your site configuration needs to look something like this:
 
@@ -342,7 +342,7 @@ An alternative approach is to make the `sidebar` entries available from a drop d
 A page that doesn't appear in any sidebar will inherit and display the first sidebar without an `id` or `title` - you can prevent the sidebar from showing on a page by setting `sidebar: false` in its front matter.
 :::
 
-![](images/nav-bar-hybrid-dropdown.png){fig-alt="A navigation bar titled 'ProjectX' on the left. To the right of the title are the menu items 'Home', 'Tutorials', 'How-To', 'Fundamentals', and 'Reference'. 'Home' is in a lighter color than the other menu options. The other menu options have a triangle pointing down next to each one, indicating the existence of a drop-down menu. There is a search bar on the far right side of the navigation bar."}
+![](images/nav-bar-hybrid-dropdown.png){.include-dark fig-alt="A navigation bar titled 'ProjectX' on the left. To the right of the title are the menu items 'Home', 'Tutorials', 'How-To', 'Fundamentals', and 'Reference'. 'Home' is in a lighter color than the other menu options. The other menu options have a triangle pointing down next to each one, indicating the existence of a drop-down menu. There is a search bar on the far right side of the navigation bar."}
 
 To achieve this, your site configuration needs to look something like this: