Add session preview to done section (#1104)

Author: cmaureir

src/content/pages/faq.mdx

@@ -22,10 +22,10 @@ subtitle: Frequently Asked Questions about EuroPython
   <li>**27 March 2025:** [Ticket sales](/tickets) open!</li>
   <li>**February/March 2025** Programme selection process</li>
   <li>**March 2025** Visa Information Page opens</li>
+  <li>**01 April 2025** Session preview</li>
 </ul>
 
 <ul className="milestone-todo">
-  <li>**01 April 2025** Session preview</li>
   <li>**20 April 2025** Schedule published</li>
   <li>**9 May 2025** Financial Aid Programme closes</li>
   <li>**14 – 20 July 2025:** EuroPython 2025!🎊 </li>