Fix doc/releases.html copy-paste mistake

Author: marijnh

doc/releases.html

@@ -30,14 +30,12 @@ <h2>Release notes and version history</h2>
 
   <h2>Version 5.x</h2>
 
-  <p class="rel">21-09-2020: <a href="https://codemirror.net/codemirror-5.58.0.zip">Version 5.58.0</a>:</p>
+  <p class="rel">21-09-2020: <a href="https://codemirror.net/codemirror-5.58.1.zip">Version 5.58.1</a>:</p>
 
   <ul class="rel-note">
     <li><a href="https://codemirror.net/doc/manual.html#addon_placeholder">placeholder addon</a>: Remove arrow function that ended up in the code.</li>
   </ul>
 
-  <h2>Version 5.x</h2>
-
   <p class="rel">21-09-2020: <a href="https://codemirror.net/codemirror-5.58.0.zip">Version 5.58.0</a>:</p>
 
   <ul class="rel-note">