Update write-metrics-md.py

Author: jukent

.github/workflows/write-metrics-md.py

@@ -28,5 +28,5 @@ def process_user_data(user_data_file, markdown_file):
 
 if __name__ == '__main__':
     user_data_file = 'user_metrics.json'
-    markdown_file = '../../portal/metrics.md'
+    markdown_file = 'portal/metrics.md'
     process_user_data(user_data_file, markdown_file)