docs: add sms demo readme

Author: timhbw

examples/sms/README.md

@@ -0,0 +1,45 @@
+# SMS Server-Side Library For PHP
+
+## Features
+
+- 签名管理
+    - [x] 创建签名: client->createSignature() 
+    - [x] 列出签名: client->checkSignature() 
+    - [x] 查询单个签名: client->checkSingleSignature() 
+    - [x] 编辑签名: client->updateSignature() 
+    - [x] 删除签名: client->deleteSignature() 
+
+- 模板管理
+    - [x] 创建模板: client->createTemplate()
+    - [x] 列出模板: client->queryTemplate()
+    - [x] 查询单个模板: client->querySingleTemplate()
+    - [x] 编辑模板: client->updateTemplate()
+    - [x] 删除模板: client->deleteTemplate()
+
+- 发送短信
+    - [x] 发送短信: client->sendMessage()
+
+- 查询发送记录
+    - [x] 查询发送记录: client->querySendSms()   
+
+## Demo
+
+- 签名管理
+    - [创建签名](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_create_signature.php) 
+    - [列出签名](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_query_signature.php) 
+    - [查询单个签名](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_query_single_signature.php) 
+    - [编辑签名](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_edit_signature.php) 
+    - [删除签名](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_delete_signature.php) 
+
+- 模板管理
+    - [创建模板](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_create_template.php)
+    - [列出模板](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_query_template.php)
+    - [查询单个模板](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_query_single_template.php)
+    - [编辑模板](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_edit_template.php)
+    - [删除模板](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_delete_template.php)
+
+- 发送短信
+    - [发送短信](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_send_message.php)    
+
+- 查询发送记录
+    - [发送短信](https://github.com/qiniu/php-sdk/tree/master/examples/sms/sms_query_send_sms.php)