adding ManageEngine as a gold sponsor for DC 2025 event

Author: znemski

data/events/2025/washington-dc/main.yml

@@ -194,6 +194,9 @@ sponsors:
     level: platinum
   - id: gruntwork
     level: platinum
+  - id: manage-engine
+    level: gold
+
  #  url: http://mysponsor.com/?campaign=me # Use this if you need to over-ride a sponsor URL.
 
 sponsors_accepted : "yes" # Whether you want "Become a XXX Sponsor!" link