Update attribution_scopes.md to remove the note as the functionality is now launched (#1493)

Update attribution_scopes.md

Author: arpanah

attribution_scopes.md

@@ -1,6 +1,5 @@
 # Pre-Attribution Filtering: Attribution Scopes
 
-_Note: This document describes possible new functionality in the Attribution Reporting API. This is a forwards and backwards compatible change to event-level and summary reports. While this new functionality is being developed, we still highly encourage testing the existing API functionalities to support core utility and compatibility needs._
 
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