doc: normalize documents

docs/formatter.md

@@ -1,15 +1,17 @@
 # Formatter
+
 formatter contains some functions for data formatting.
 
 <div STYLE="page-break-after: always;"></div>
 
 ## Source:
 
-- [https://github.com/duke-git/lancet/blob/main/formatter/formatter.go](https://github.com/duke-git/lancet/blob/main/formatter/formatter.go)
+-   [https://github.com/duke-git/lancet/blob/main/formatter/formatter.go](https://github.com/duke-git/lancet/blob/main/formatter/formatter.go)
 
 <div STYLE="page-break-after: always;"></div>
 
 ## Usage:
+
 ```go
 import (
     "github.com/duke-git/lancet/v2/formatter"
@@ -19,15 +21,15 @@ import (
 <div STYLE="page-break-after: always;"></div>
 
 ## Index
-- [Comma](#Comma)
+
+-   [Comma](#Comma)
 
 <div STYLE="page-break-after: always;"></div>
 
 ## Documentation
 
-
-
 ### <span id="Comma">Comma</span>
+
 <p>Add comma to a number value by every 3 numbers from right to left. ahead by symbol char. if value is a invalid number string like "aa", return empty string.</p>
 
 <b>Signature:</b>
@@ -35,6 +37,7 @@ import (
 ```go
 func Comma[T constraints.Float | constraints.Integer | string](value T, symbol string) string
 ```
+
 <b>Example:</b>
 
 ```go
@@ -46,7 +49,17 @@ import (
 )
 
 func main() {
-    fmt.Println(formatter.Comma("12345", ""))   // "12,345"
-    fmt.Println(formatter.Comma(12345.67, "¥")) // "¥12,345.67"
+    result1 := formatter.Comma("123", "")
+    result2 := formatter.Comma("12345", "$")
+    result3 := formatter.Comma(1234567, "￥")
+
+    fmt.Println(result1)
+    fmt.Println(result2)
+    fmt.Println(result3)
+
+    // Output:
+    // 123
+    // $12,345
+    // ￥1,234,567
 }
 ```