Clarify that modifying img.referrerPolicy is not a relevant mutation

index.html

@@ -1425,6 +1425,7 @@ <h3 class="heading settled" data-level="5.3" id="html-image-element"><span class
     <h4 class="heading settled" data-level="5.3.1" id="html-image-element-attributes"><span class="secno">5.3.1. </span><span class="content">Attributes</span><a class="self-link" href="#html-image-element-attributes"></a></h4>
      The <code>referrerPolicy</code> IDL attribute must <a data-link-type="dfn" href="http://www.w3.org/TR/html5/infrastructure.html#reflect">reflect</a> the <code>referrerpolicy</code> content attribute, <a data-link-type="dfn" href="http://www.w3.org/TR/html5/infrastructure.html#limited-to-only-known-values">limited to only known
   values</a>. 
+    <p class="note" role="note">Note: Modifying the <code>referrerPolicy</code> IDL attribute is not a <a data-link-type="dfn" href="http://www.w3.org/TR/html5/embedded-content-0.html#relevant-mutations">relevant mutation</a> for an <code><a data-link-type="element" href="https://html.spec.whatwg.org/multipage/embedded-content.html#the-img-element">img</a></code> element.</p>
     <h3 class="heading settled" data-level="5.4" id="html-iframe-element"><span class="secno">5.4. </span><span class="content">HTMLIFrameElement</span><a class="self-link" href="#html-iframe-element"></a></h3>
 <pre class="idl">partial interface <a class="idl-code" data-link-type="interface" href="https://html.spec.whatwg.org/multipage/embedded-content.html#htmliframeelement">HTMLIFrameElement</a> {
   attribute DOMString <dfn class="idl-code" data-dfn-for="HTMLIFrameElement" data-dfn-type="attribute" data-export="" data-type="DOMString " id="dom-htmliframeelement-referrerpolicy">referrerPolicy<a class="self-link" href="#dom-htmliframeelement-referrerpolicy"></a></dfn>;
@@ -1763,6 +1764,7 @@ <h3 class="no-num heading settled" id="index-defined-elsewhere"><span class="con
      <li><a href="http://www.w3.org/TR/html5/links.html#link-type-noreferrer">noreferrer</a>
      <li><a href="http://www.w3.org/TR/html5/browsers.html#parent-browsing-context">parent browsing context</a>
      <li><a href="http://www.w3.org/TR/html5/infrastructure.html#reflect">reflect</a>
+     <li><a href="http://www.w3.org/TR/html5/embedded-content-0.html#relevant-mutations">relevant mutation</a>
      <li><a href="http://www.w3.org/TR/html5/webappapis.html#responsible-browsing-context">responsible browsing context</a>
      <li><a href="http://www.w3.org/TR/html5/webappapis.html#settings-object">settings object</a>
      <li><a href="http://www.w3.org/TR/html5/infrastructure.html#strip-leading-and-trailing-whitespace">strip leading and trailing whitespace</a>
@@ -1877,4 +1879,4 @@ <h2 class="no-num heading settled" id="idl-index"><span class="content">IDL Inde
 
 </pre>
  </body>
-</html>
+</html>

index.src.html

@@ -53,6 +53,7 @@ <h1>Referrer Policy</h1>
       text: the document's address
     urlPrefix: embedded-content-0.html
       text: an iframe srcdoc document
+      text: relevant mutation; url: relevant-mutations
     urlPrefix: browsers.html
       text: active document
       text: parse a sandboxing directive
@@ -645,6 +646,9 @@ <h4 id="html-image-element-attributes">Attributes</h4>
   <code>referrerpolicy</code> content attribute, <a>limited to only known
   values</a>.
 
+  Note: Modifying the <code>referrerPolicy</code> IDL attribute is not a
+  <a>relevant mutation</a> for an <code><a element>img</a></code> element.
+
   <h3 id="html-iframe-element">HTMLIFrameElement</h3>
   <pre class="idl">
     partial interface HTMLIFrameElement {