Add text to board nominations page to make it clear it isn't current.

Author: myShoggoth

docs/board-nominations/index.html

@@ -184,6 +184,7 @@
 
 
 
+<div class="text-center text-xl">Note: This page is for historical purposes, the call for nominations has expired.</div>
   <div class="max-w-screen-xl mx-auto py-16 md:py-24">
     <div class="sm:px-6 lg:px-16">
       <div class="relative">