Rename warning field to warn in the output

log.go

@@ -101,7 +101,7 @@ func (l Level) String() string {
 	case InfoLevel:
 		return "info"
 	case WarnLevel:
-		return "warning"
+		return "warn"
 	case ErrorLevel:
 		return "error"
 	case FatalLevel:

log_example_test.go

@@ -78,7 +78,7 @@ func ExampleLogger_Warn() {
 		Str("foo", "bar").
 		Msg("a warning message")
 
-	// Output: {"level":"warning","foo":"bar","message":"a warning message"}
+	// Output: {"level":"warn","foo":"bar","message":"a warning message"}
 }
 
 func ExampleLogger_Error() {

log_test.go

@@ -243,7 +243,7 @@ func TestLevelWriter(t *testing.T) {
 	}{
 		{DebugLevel, `{"level":"debug","message":"1"}` + "\n"},
 		{InfoLevel, `{"level":"info","message":"2"}` + "\n"},
-		{WarnLevel, `{"level":"warning","message":"3"}` + "\n"},
+		{WarnLevel, `{"level":"warn","message":"3"}` + "\n"},
 		{ErrorLevel, `{"level":"error","message":"4"}` + "\n"},
 	}
 	if got := lw.ops; !reflect.DeepEqual(got, want) {

syslog_test.go

@@ -49,7 +49,7 @@ func TestSyslogWriter(t *testing.T) {
 	want := []syslogEvent{
 		{"Debug", `{"level":"debug","message":"debug"}` + "\n"},
 		{"Info", `{"level":"info","message":"info"}` + "\n"},
-		{"Warning", `{"level":"warning","message":"warn"}` + "\n"},
+		{"Warning", `{"level":"warn","message":"warn"}` + "\n"},
 		{"Err", `{"level":"error","message":"error"}` + "\n"},
 	}
 	if got := sw.events; !reflect.DeepEqual(got, want) {

writer_test.go

@@ -15,7 +15,7 @@ func TestMultiSyslogWriter(t *testing.T) {
 	want := []syslogEvent{
 		{"Debug", `{"level":"debug","message":"debug"}` + "\n"},
 		{"Info", `{"level":"info","message":"info"}` + "\n"},
-		{"Warning", `{"level":"warning","message":"warn"}` + "\n"},
+		{"Warning", `{"level":"warn","message":"warn"}` + "\n"},
 		{"Err", `{"level":"error","message":"error"}` + "\n"},
 	}
 	if got := sw.events; !reflect.DeepEqual(got, want) {