Add a new pseudo element search-text

Author: jihyerish

css-pseudo-4/Overview.bs

@@ -570,7 +570,7 @@ Styling the First-Letter Pseudo-elements</h4>
 Highlight Pseudo-elements</h2>
 
 <h3 id="highlight-selectors">
-Selecting Highlighted Content: the ''::selection'',  ''::target-text'', ''::spelling-error'', and ''::grammar-error'' pseudo-elements</h3>
+Selecting Highlighted Content</h3>
 
   The <dfn export lt="highlight pseudo-element">highlight pseudo-elements</dfn>
   represent portions of a document that have been given a particular status
@@ -641,6 +641,12 @@ Selecting Highlighted Content: the ''::selection'',  ''::target-text'', ''::spel
       css/css-pseudo/grammar-error-002-manual.html
       css/css-pseudo/grammar-error-003-manual.html
       </wpt>
+
+    <dt><dfn>::search-text</dfn>
+    <dd>
+      The ''::search-text'' pseudo-element represents
+      texts that are the results shown when using the user agent’s find-in-page feature.
+
   </dl>
 
   The <a>highlight pseudo-elements</a>