Change subsections to be hierarchical headings in README (#574)

SHA: 636ff69
Reason: push, by jyasskin

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

Author: csarven

index.html

@@ -8,7 +8,7 @@
   <meta content="Bikeshed version b25686b9f, updated Fri Mar 14 14:15:20 2025 -0700" name="generator">
   <link href="https://www.w3.org/TR/design-principles/" rel="canonical">
   <link href="https://www.w3.org/2008/site/images/favicon.ico" rel="icon">
-  <meta content="8b0f2a8705a876865e44116cb16853cb1154aa72" name="revision">
+  <meta content="636ff69ccc6db8f37a95ef136776f864e7f7e2c0" name="revision">
   <meta content="dark light" name="color-scheme">
   <link href="https://www.w3.org/StyleSheets/TR/2021/dark.css" media="(prefers-color-scheme: dark)" rel="stylesheet" type="text/css">
 <style>
@@ -702,7 +702,7 @@
   <div class="head">
    <p data-fill-with="logo"><a class="logo" href="https://www.w3.org/"> <img alt="W3C" height="48" src="https://www.w3.org/StyleSheets/TR/2021/logos/W3C" width="72"> </a> </p>
    <h1 class="p-name no-ref" id="title">Web Platform Design Principles</h1>
-   <p id="w3c-state"><a href="https://www.w3.org/standards/types/#ED">Editor’s Draft</a>, <time class="dt-updated" datetime="2025-05-19">19 May 2025</time></p>
+   <p id="w3c-state"><a href="https://www.w3.org/standards/types/#ED">Editor’s Draft</a>, <time class="dt-updated" datetime="2025-05-22">22 May 2025</time></p>
    <details open>
     <summary>More details about this document</summary>
     <div data-fill-with="spec-metadata">