Update changelog to add PayPal plugin

Author: ywarnier

documentation/changelog.html

@@ -85,6 +85,7 @@ <h3>New Features</h3>
     <li>(#7072) Added user profile fields of type "File upload"</li>
     <li>(BT#7010) Add Aiken (Word) import format in exercises</li>
     <li>(#6224) Add browser language auto-detection at first connection</li>
+    <li>(#5464) Added BuyCourses plugin for PayPal payments</li>
 </ul>
 <h3>Improvements (minor features)</h3>
 <ul>