Adds notice to admin about available updates

bookwyrm/templates/settings/dashboard/dashboard.html

@@ -48,6 +48,7 @@
         </a>
     </div>
     {% endif %}
+
     {% if pending_domains %}
     <div class="column">
         <a href="{% url 'settings-link-domain' %}" class="notification is-primary is-block">
@@ -59,9 +60,10 @@
         </a>
     </div>
     {% endif %}
+
     {% if not site.allow_registration and site.allow_invite_requests and invite_requests %}
     <div class="column">
-        <a href="{% url 'settings-invite-requests' %}" class="notification is-block is-success is-light">
+        <a href="{% url 'settings-invite-requests' %}" class="notification is-block is-success">
             {% blocktrans trimmed count counter=invite_requests with display_count=invite_requests|intcomma %}
             {{ display_count }} invite request
             {% plural %}
@@ -70,6 +72,16 @@
         </a>
     </div>
     {% endif %}
+
+    {% if current_version %}
+    <div class="column">
+        <a href="https://docs.joinbookwyrm.com/updating-your-instance.html" class="notification is-block is-warning" target="_blank">
+            {% blocktrans trimmed with current=current_version available=available_version %}
+            An update is available! You're running v{{ current }} and the latest release is {{ available }}.
+            {% endblocktrans %}
+        </a>
+    </div>
+    {% endif %}
 </div>
 
 <div class="block content">