note on measurements

Author: mydea

docs/platforms/javascript/common/tracing/span-metrics/index.mdx

@@ -133,3 +133,8 @@ When implementing span metrics in your application:
    - Ensure metrics can drive issue resolution or decision making
 
 For detailed examples of how to implement span metrics in common scenarios, see our <PlatformLink to="/tracing/span-metrics/examples/">Span Metrics Examples</PlatformLink> guide.
+
+## Span Metrics vs. Measurements
+
+Previously, Sentry supported adding metrics to transactions using the `Sentry.setMeasurement()` API.
+This approach is deprecated, you should use span attributes instead.