add dark mode ToC image

Author: ethanpalm

guides/changelogs.mdx

@@ -12,8 +12,17 @@ Check out the [Mintlify changelog](/changelog) as an example: you can include li
 
 Each `Update` element label is automatically used to create a table of contents on the right side of the page:
 
-<Frame caption="Table of contents">
-![Changelogs with table of contents](/images/changelog-toc.png)
+<Frame>
+  <img 
+    src="/images/changelog-toc-light.png" 
+    alt="Changelog with table of contents displayed in light mode." 
+    className="block dark:hidden" 
+  />
+  <img 
+    src="/images/changelog-toc-dark.png" 
+    alt="Changelog with table of contents displayed in dark mode." 
+    className="hidden dark:block" 
+  />
 </Frame>
 
 ## Tag filters