add migration notice to site

Author: drusepth

app/views/layouts/application.html.erb

@@ -11,6 +11,13 @@
   <%= render 'layouts/navbar' %>
 
   <main>
+    <div class="card-panel yellow">
+      <strong>Notice:</strong> Notebook.ai will be down for scheduled maintenance on <strong>Feburary 16<sup>th</sup></strong>, starting at 5PM Pacific, to move to a more stable host.
+      The migration should take about 4 hours.
+      You can <%= link_to 'join the Notebook.ai discord', 'https://discord.gg/R9vsXq8ysQ' %> for updates during the migration.
+      <br />
+    </div>
+
     <%= yield :full_width_page_header %>
     <%= yield :full_width_page_content %>
     <div class="container<% if (user_signed_in? && current_user.fluid_preference) || request.env.fetch('REQUEST_PATH', '').start_with?('/forum/') || @full_width_page_override %>-fluid<% end %>">