Fix incorrect submit add-on hyperlink (#4)

Author: limafresh

layouts/partials/nav.html

@@ -8,7 +8,7 @@
     <div class="w-2/3 max-md:w-full">
       <h1 class="text-5xl md:text-7xl font-semibold">Add-ons</h1>
       <p class="text-xl text-neutral-400 mt-2">Add-on widgets and containers for the Fyne toolkit.
-        <br><a href="https://docs.fyne.io/submit/addon" class="text-primary-400 hover:underline">Submit yours here</a>
+        <br><a href="https://docs.fyne.io/submit-addon" class="text-primary-400 hover:underline">Submit yours here</a>
       </p>
     </div>
     <div class="flex items-center gap-1 cursor-pointer mt-4">