adjust signal termination warning log

Signed-off-by: machine424 <ayoubmrini424@gmail.com>

cmd/prometheus/main.go

@@ -960,8 +960,8 @@ func main() {
 			func() error {
 				// Don't forget to release the reloadReady channel so that waiting blocks can exit normally.
 				select {
-				case <-term:
-					level.Warn(logger).Log("msg", "Received SIGTERM, exiting gracefully...")
+				case sig := <-term:
+					level.Warn(logger).Log("msg", "Received an OS signal, exiting gracefully...", "signal", sig.String())
 					reloadReady.Close()
 				case <-webHandler.Quit():
 					level.Warn(logger).Log("msg", "Received termination request via web service, exiting gracefully...")