Changes section: explicit headings

Use explicit headings in an attempt to reduce/eliminate bikeshed warnings

Vision/Vision.bs

@@ -198,8 +198,8 @@ Markup Shorthands: markdown yes
 		It is not intended to supplant that work nor redefine it,
 		but fit into the same framework and promote many of the same goals.
 
-# Changes
-## Changes from <a href="https://www.w3.org/TR/2024/NOTE-w3c-vision-20240403/">2024-04-03 Note</a>
+<h2 id="changes">Changes</h2>
+<h3 id="changes-from-2024-04-03">Changes from <a href="https://www.w3.org/TR/2024/NOTE-w3c-vision-20240403/">2024-04-03 Note</a></h2>
 View <a href="https://services.w3.org/htmldiff?doc1=https%3A%2F%2Fwww.w3.org%2FTR%2Fw3c-vision%2F&doc2=https%3A%2F%2Fw3c.github.io%2FAB-public%2FVision">differences between Editor’s Draft and First Public Group Note</a>
 <ul>
 <li>Status of this document: <ul>