Add changelog entry

Author: MrAlias

CHANGELOG.md

@@ -22,6 +22,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Fix inconsistent request body closing in `go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp`. (#5954)
 - Fix inconsistent request body closing in `go.opentelemetry.io/otel/exporters/otlp/otlpmetric/otlpmetrichttp`. (#5954)
 - Fix invalid exemplar keys in `go.opentelemetry.io/otel/exporters/prometheus`. (#5995)
+- Fix attribute value truncation in `go.opentelemetry.io/otel/sdk/trace`. (#5997)
 
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