update doc

Signed-off-by: Nshawn_he <shawn.he@huawei.com>

en/application-dev/internationalization/i18n-guidelines.md

@@ -53,7 +53,6 @@ You can use APIs provided in the following table to obtain the system language a
 
     Call the **isRTL** method to check whether the locale's language is RTL.
    
-   
    ```js
    var rtl = i18n.isRTL("zh-CN");
    ```
@@ -217,6 +216,7 @@ You can use APIs provided in the following table to obtain the system language a
    ```
 
 2. Check whether the phone number format is correct.
+
     Call the **isValidNumber** method to check whether the format of the input phone number is correct.
      
    ```js
@@ -224,6 +224,7 @@ You can use APIs provided in the following table to obtain the system language a
    ```
 
 3. Format a phone number.
+
     Call the **format** method of **PhoneNumberFormat** to format the input phone number.
      
    ```js
@@ -245,8 +246,7 @@ The **unitConvert** API is provided to help you implement measurement conversion
 
 ### How to Develop
 
-1. Convert a measurement unit.
-   Call the [unitConvert](../reference/apis/js-apis-i18n.md#unitconvert8) method to convert a measurement unit and format the display result.
+Call the [unitConvert](../reference/apis/js-apis-i18n.md#unitconvert8) method to convert a measurement unit and format the display result.
 
    
    ```js