Add preview widget changelog entry (#2158)

* Update changelog.mdx

Co-Authored-By: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>

* Update changelog.mdx

---------

Co-authored-by: mintlify[bot] <109931778+mintlify[bot]@users.noreply.github.com>
Co-authored-by: Ethan Palm <[email protected]>

Author: 3 people

changelog.mdx

@@ -5,6 +5,18 @@ rss: true
 noindex: true
 ---
 
+<Update label="December 9, 2025" tags={["New releases"]} rss={{ title: "Preview widget", description: "Track changed files in preview deployments with an interactive widget" }}>
+  ## Preview widget
+
+  Preview deployments now include an interactive widget that displays all changed files in the deployment. The widget appears as a floating button in the bottom-right corner and provides:
+
+    - One-click navigation to changed pages.  
+    - Searchable list of all changed files with status badges (added, modified, removed).
+
+  The widget is automatically enabled on all preview deployments and helps reviewers quickly navigate to modified content.
+
+</Update>
+
 <Update label="December 8, 2025" tags={["New releases"]} rss={{ title: "Last modified dates", description: "Show when pages were last updated with automatic timestamps" }}>
   ## Last modified dates