更新注释信息

encoding.go

@@ -33,7 +33,7 @@ func (c *Carbon) UnmarshalJSON(b []byte) error {
 	if c.Error != nil {
 		return c.Error
 	}
-	if string(b) == "null" || len(b) == 0 {
+	if len(b) == 0 || string(b) == "null" {
 		return nil
 	}
 	key, value, tz := c.parseTag()

getter.go

@@ -4,8 +4,8 @@ import (
 	"time"
 )
 
-// StdTime converts Carbon to standard time.Time.
-// 将 Carbon 转换成标准 time.Time
+// StdTime gets standard time.Time.
+// 获取标准 time.Time
 func (c Carbon) StdTime() time.Time {
 	return c.time.In(c.loc)
 }