Update navigation link from Fred to ZDTT

Author: ZaneThePython

index.html

@@ -48,13 +48,13 @@ <h2 id="about-heading" class="sr-only">About</h2>
       <!-- Navigation Section -->
       <nav class="navigation" role="navigation" aria-label="Main navigation">
         <a
-          href="https://fred.zane.org"
+          href="https://zdtt.zane.org"
           class="nav-button"
           target="_blank"
           rel="noopener noreferrer"
-          aria-label="Visit Fred: Origins (opens in new tab)"
+          aria-label="Explore and try ZDTT (opens in new tab)"
         >
-          <span>Fred: Origins</span>
+          <span>ZDTT</span>
         </a>
         <a
           href="https://github.com/ZaneThePython"