update README.md

Author: SFantasy

README.md

@@ -11,12 +11,20 @@ String validator for more.
 
 ## Usage
 
-### Node.js
-
 ```
 var validator = require('is-valid');
+
+validator.isEmail('abc@gmail.com'); // => true
 ```
 
+### Validators
+
+- isEmail(str): check if it is an Email string
+- isAllChinese(str): check if it is a string only contains Chinese characters
+- isAllEnglish(str): check if it is a string only contains English characters
+- isAllDigit(str): check if it is a string only contains digits
+- isChineseTel(str): check if it is a Chinese cell-phone number
+
 ## License
 
 The MIT License