add changelog

Author: sghall

changelog.d/15687_syslog_udp_received_metrics.fix.md

@@ -0,0 +1,10 @@
+The `syslog` source in UDP mode now emits the standard "received" metrics, aligning behavior with TCP and the Component Specification:
+
+- `component_received_events_total`
+- `component_received_event_bytes_total`
+- `component_received_bytes_total`
+
+This makes internal telemetry consistent and restores compliance checks for UDP syslog.
+
+authors: sghall
+