[css-pseudo-4] Move text to more appropriate section

Author: fantasai

css-pseudo-4/Overview.bs

@@ -479,15 +479,6 @@ Selecting Highlighted Content: the ''::selection'',  ''::inactive-selection'', '
   do not necessarily fit into the element tree,
   and can arbitrarily cross element boundaries without honoring its nesting structure.
 
-    The following addition is made to the default UA stylesheet:
-	<pre><code class="lang-css">
-		/* Represent default spelling/grammar error styling in an adjustable way */
-		:root::spelling-error { text-decoration-line: spelling-error; }
-		:root::grammar-error  { text-decoration-line: grammar-error; }
-		/* Ensure contrast on text with shadows */
-		:root::selection      { text-shadow: none; }
-	</code></pre>
-
   Note: A future level of CSS may introduce ways to create
   custom highlight pseudo-elements.
 
@@ -545,6 +536,15 @@ Styling Highlights</h3>
   Note: Historically (and at the time of writing)
   only 'color' and 'background-color' have been interoperably supported.
 
+  The following addition is made to the default UA stylesheet:
+  <pre><code class="lang-css">
+    /* Represent default spelling/grammar error styling in an adjustable way */
+    :root::spelling-error { text-decoration-line: spelling-error; }
+    :root::grammar-error  { text-decoration-line: grammar-error; }
+    /* Ensure contrast on text with shadows */
+    :root::selection      { text-shadow: none; }
+  </code></pre>
+
 <h3 id=highlight-bounds>
 Area of a Highlight</h3>