vendor: add qingstor-sdk-go for QingStor

vendor/github.com/yunify/qingstor-sdk-go/docs/configuration.md

@@ -0,0 +1,69 @@
+# Configuration Guide
+
+## Summary
+
+This SDK uses a structure called "Config" to store and manage configuration, read comments of public functions in ["config/config.go"](https://github.com/yunify/qingstor-sdk-go/blob/master/config/config.go) for details.
+
+Except for Access Key, you can also configure the API endpoint for private cloud usage scenario. All available configurable items are listed in the default configuration file.
+
+___Default Configuration File:___
+
+``` yaml
+# QingStor services configuration
+
+access_key_id: 'ACCESS_KEY_ID'
+secret_access_key: 'SECRET_ACCESS_KEY'
+
+host: 'qingstor.com'
+port: 443
+protocol: 'https'
+connection_retries: 3
+
+# Valid log levels are "debug", "info", "warn", "error", and "fatal".
+log_level: 'warn'
+
+```
+
+## Usage
+
+Just create a config structure instance with your API Access Key, and initialize services you need with Init() function of the target service.
+
+### Code Snippet
+
+Create default configuration
+
+``` go
+defaultConfig, _ := config.NewDefault()
+```
+
+Create configuration from Access Key
+
+``` go
+configuration, _ := config.New("ACCESS_KEY_ID", "SECRET_ACCESS_KEY")
+
+anotherConfiguration := config.NewDefault()
+anotherConfiguration.AccessKeyID = "ACCESS_KEY_ID"
+anotherConfiguration.SecretAccessKey = "SECRET_ACCESS_KEY"
+```
+
+Load user configuration
+
+``` go
+userConfig, _ := config.NewDefault().LoadUserConfig()
+```
+
+Load configuration from config file
+
+``` go
+configFromFile, _ := config.NewDefault().LoadConfigFromFilepath("PATH/TO/FILE")
+```
+
+Change API endpoint
+
+``` go
+moreConfiguration, _ := config.NewDefault()
+
+moreConfiguration.Protocol = "http"
+moreConfiguration.Host = "api.private.com"
+moreConfiguration.Port = 80
+```