add maintenance window

announcement.md

-# 2025-05-05 Research Computing Customer Survey
+### 2025-05-13 Maintenance Window
 
-Dear UAB Research Computing Community,
+Cheaha will be impacted by a maintenance window Jul 16, 2025, through Jul 22, 2025. Read more on our docs at our [News Page](https://docs.rc.uab.edu/news/#2025-05-13-planned-maintenance-window).
+
+### 2025-05-05 Research Computing Customer Survey
 
 We invite you to complete our brief Research Computing [Survey](https://uab.co1.qualtrics.com/jfe/form/SV_dbaFBqVXIVkSbum) by Friday, May 16 to share your experience and suggestions—it takes less than 5 minutes.
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