fixes deprecated docs warning on v1.0+ (#4599)

Co-authored-by: Paul S. Schweigert <paulschw@us.ibm.com>

overrides/main.html

@@ -4,6 +4,7 @@
 <meta name="theme-color" content="#1a7dc9" />
 {% endblock %}
 
+{% block announce %}
 {% if config.extra.version_warning %}
 <div class="versionwarning" style="margin: .6rem auto; padding: 0 .8rem">
   <h1>⚠ You are viewing an archived snapshot of the documentation for Knative version: {{ config.extra.knative_version }}</h1>
@@ -11,11 +12,11 @@
   Knative {{ config.extra.knative_version }} documentation is no longer actively maintained. The documentation you are currently viewing is a static snapshot. For up-to-date documentation, see <a href="{{ base_url }}/../docs/">the latest version</a>.
   </p>
 </div>
-{% endif %}
-{% block announce %}
+{% else %}
 <div class="versionwarning" style="display: flex; justify-content: center;">
   <p>Knative is 1.0! 🎉  Check out our announcement on the <a href=https://knative.dev/blog/articles/knative-1.0/>Knative Blog<a/></p>
 </div>
+{% endif %}
 {% endblock %}
 
 {% block scripts %}