added maintenance info for Tuesday June 18 from 9-11 AM (#206)

* added maintenance infor for June 18 9-11 AM

* updated the url slug with timestamp

* updated the timestamp date

* 9-11AM instead of 8-11AM

nerc-theme/main.html

@@ -2,16 +2,16 @@
 
 {% block announce %}
 <div class="parent">
-  <!-- <div class="maintain">
+  <div class="maintain">
     <div>
-      Upcoming MGHPCC (Holyoke) Annual Power Shutdown
+      Upcoming RegApp & ColdFront service upgrade and maintenance
     </div>
-    <div>[May 22, 2023 8:00 AM ET - May 28, 2023 8:00 PM ET])
+    <div>[June 18, 2024 9:00 AM - 11:00 AM ET])
       <a style="color: #00efff;"
-        href="https://nerc.mghpcc.org/event/mghpcc-annual-power-shutdown-2024/"
+        href="https://nerc.mghpcc.org/event/regapp-coldfront-upgrade-maintenance-20240618/"
         target="_blank">[Timeline and info]</a>
     </div>
-  </div> -->
+  </div>
   <div class="child">
     <iframe src="https://nerc.instatus.com/embed-status/light-sm" width="230" height="52" frameBorder="0" scrolling="no" style="border: none;" ></iframe>
   </div>