Fix has_one example references value (#770)

pages/docs/has_one.md

@@ -68,7 +68,7 @@ You are able to change it with tag `references`, e.g:
 type User struct {
  gorm.Model
  Name string `gorm:"index"`
- CreditCard CreditCard `gorm:"foreignKey:UserName;references:name"`
+ CreditCard CreditCard `gorm:"foreignKey:UserName;references:Name"`
 }
 
 type CreditCard struct {